Jan Beulich
2011-Oct-13 07:21 UTC
[Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
The IDTs being exactly a page in size, using xmalloc() here is rather
inefficient, as this requires double the amount to be allocated (with
almost an entire page wasted). For hot plugged CPUs, this at once
eliminates one more non-order-zero runtime allocation.
For x86-32, however, the IDT is exactly half a page, so allocating a
full page seems wasteful here, so it continues to use xmalloc() as
before.
With most of the affected functions'' bodies now being inside #ifdef-s,
it might be reasonable to split those parts out into subarch-specific
code...
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -639,9 +639,6 @@ static void cpu_smpboot_free(unsigned in
{
unsigned int order;
- xfree(idt_tables[cpu]);
- idt_tables[cpu] = NULL;
-
order = get_order_from_pages(NR_RESERVED_GDT_PAGES);
#ifdef __x86_64__
if ( per_cpu(compat_gdt_table, cpu) )
@@ -650,10 +647,15 @@ static void cpu_smpboot_free(unsigned in
free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)),
order);
per_cpu(compat_gdt_table, cpu) = NULL;
+ order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables));
+ if ( idt_tables[cpu] )
+ free_domheap_pages(virt_to_page(idt_tables[cpu]), order);
#else
free_xenheap_pages(per_cpu(gdt_table, cpu), order);
+ xfree(idt_tables[cpu]);
#endif
per_cpu(gdt_table, cpu) = NULL;
+ idt_tables[cpu] = NULL;
if ( stack_base[cpu] != NULL )
{
@@ -691,19 +693,25 @@ static int cpu_smpboot_alloc(unsigned in
if ( !page )
goto oom;
per_cpu(gdt_table, cpu) = gdt = page_to_virt(page);
+ order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables));
+ page = alloc_domheap_pages(NULL, order,
+ MEMF_node(cpu_to_node(cpu)));
+ if ( !page )
+ goto oom;
+ idt_tables[cpu] = page_to_virt(page);
#else
per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0);
if ( !gdt )
goto oom;
+ idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES);
+ if ( idt_tables[cpu] == NULL )
+ goto oom;
#endif
memcpy(gdt, boot_cpu_gdt_table,
NR_RESERVED_GDT_PAGES * PAGE_SIZE);
BUILD_BUG_ON(NR_CPUS > 0x10000);
gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu;
- idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES);
- if ( idt_tables[cpu] == NULL )
- goto oom;
memcpy(idt_tables[cpu], idt_table,
IDT_ENTRIES*sizeof(idt_entry_t));
_______________________________________________
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Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
Keir Fraser
2011-Oct-13 07:50 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
On 13/10/2011 08:21, "Jan Beulich" <JBeulich@suse.com> wrote:> The IDTs being exactly a page in size, using xmalloc() here is rather > inefficient, as this requires double the amount to be allocated (with > almost an entire page wasted). For hot plugged CPUs, this at once > eliminates one more non-order-zero runtime allocation. > > For x86-32, however, the IDT is exactly half a page, so allocating a > full page seems wasteful here, so it continues to use xmalloc() as > before. > > With most of the affected functions'' bodies now being inside #ifdef-s, > it might be reasonable to split those parts out into subarch-specific > code...Well, there is also opportunity for code merging. There is generally no reason for x86-64 to use alloc_domheap_pages where x86-32 uses alloc_xenheap_pages (e.g., for allocating per_cpu(gdt_table)) -- both architectures can use alloc_xenheap_pages in this case. Also we might get rid of some further ifdef''ery if we added an alloc/free interface where *both* functions take a size parameter. We could then decide whether to use xmalloc or alloc_xenheap_pages dynamically based on that parameter. Knowing size on free would allow us to easily free such allocations too. Finally, I''m not sure about more x86-64 code movement: I''d like to kill x86-32 entirely really. Anyway, despite all this...> Signed-off-by: Jan Beulich <jbeulich@suse.com>Acked-by: Keir Fraser <keir@xen.org>> --- a/xen/arch/x86/smpboot.c > +++ b/xen/arch/x86/smpboot.c > @@ -639,9 +639,6 @@ static void cpu_smpboot_free(unsigned in > { > unsigned int order; > > - xfree(idt_tables[cpu]); > - idt_tables[cpu] = NULL; > - > order = get_order_from_pages(NR_RESERVED_GDT_PAGES); > #ifdef __x86_64__ > if ( per_cpu(compat_gdt_table, cpu) ) > @@ -650,10 +647,15 @@ static void cpu_smpboot_free(unsigned in > free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), > order); > per_cpu(compat_gdt_table, cpu) = NULL; > + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); > + if ( idt_tables[cpu] ) > + free_domheap_pages(virt_to_page(idt_tables[cpu]), order); > #else > free_xenheap_pages(per_cpu(gdt_table, cpu), order); > + xfree(idt_tables[cpu]); > #endif > per_cpu(gdt_table, cpu) = NULL; > + idt_tables[cpu] = NULL; > > if ( stack_base[cpu] != NULL ) > { > @@ -691,19 +693,25 @@ static int cpu_smpboot_alloc(unsigned in > if ( !page ) > goto oom; > per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); > + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); > + page = alloc_domheap_pages(NULL, order, > + MEMF_node(cpu_to_node(cpu))); > + if ( !page ) > + goto oom; > + idt_tables[cpu] = page_to_virt(page); > #else > per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); > if ( !gdt ) > goto oom; > + idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); > + if ( idt_tables[cpu] == NULL ) > + goto oom; > #endif > memcpy(gdt, boot_cpu_gdt_table, > NR_RESERVED_GDT_PAGES * PAGE_SIZE); > BUILD_BUG_ON(NR_CPUS > 0x10000); > gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; > > - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); > - if ( idt_tables[cpu] == NULL ) > - goto oom; > memcpy(idt_tables[cpu], idt_table, > IDT_ENTRIES*sizeof(idt_entry_t)); > > > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jan Beulich
2011-Oct-13 07:55 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
>>> On 13.10.11 at 09:50, Keir Fraser <keir@xen.org> wrote: > Finally, I''m not sure about more x86-64 code movement: I''d like to kill > x86-32 entirely really.I know, but you got pushed back each time you tried... Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2011-Oct-13 08:15 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
On 13/10/2011 08:55, "Jan Beulich" <JBeulich@suse.com> wrote:>>>> On 13.10.11 at 09:50, Keir Fraser <keir@xen.org> wrote: >> Finally, I''m not sure about more x86-64 code movement: I''d like to kill >> x86-32 entirely really. > > I know, but you got pushed back each time you tried...I think we''re stuck with it for 4.2. Will try again when we open development for 4.3. The argument last time was the low-powered Atoms, used in low-end netbooks; but there''s no evidence that anyone is using Xen on such platforms. I can''t imagine it would be very worthwhile. -- Keir> Jan >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2011-Oct-13 09:34 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
On 13/10/2011 08:50, "Keir Fraser" <keir@xen.org> wrote:> On 13/10/2011 08:21, "Jan Beulich" <JBeulich@suse.com> wrote: > >> The IDTs being exactly a page in size, using xmalloc() here is rather >> inefficient, as this requires double the amount to be allocated (with >> almost an entire page wasted). For hot plugged CPUs, this at once >> eliminates one more non-order-zero runtime allocation. >> >> For x86-32, however, the IDT is exactly half a page, so allocating a >> full page seems wasteful here, so it continues to use xmalloc() as >> before. >> >> With most of the affected functions'' bodies now being inside #ifdef-s, >> it might be reasonable to split those parts out into subarch-specific >> code... > > Well, there is also opportunity for code merging. There is generally no > reason for x86-64 to use alloc_domheap_pages where x86-32 uses > alloc_xenheap_pages (e.g., for allocating per_cpu(gdt_table)) -- both > architectures can use alloc_xenheap_pages in this case. > > Also we might get rid of some further ifdef''ery if we added an alloc/free > interface where *both* functions take a size parameter. We could then decide > whether to use xmalloc or alloc_xenheap_pages dynamically based on that > parameter. Knowing size on free would allow us to easily free such > allocations too. > > Finally, I''m not sure about more x86-64 code movement: I''d like to kill > x86-32 entirely really.Given our antipathy to the x86-32 hypervisor, and the fact that any remaining users of it are unlikely to be running MP systems at all let alone large MP systems, how about this cleanup patch?... (It looks quite confusing as a patch, actually, but does the obvious thing). -- Keir x86: Simplify smpboot_alloc by merging x86-{32,64} code as far as possible. We still need one ifdef, as x86-32 does not have a compat_gdt_table. On x86-32 there is 1/2-page wastage due to allocating a whole page for the per-CPU IDT, however we expect very few users of the x86-32 hypervisor. Those that cannot move to the 64-bit hypervisor are likely using old single-processor systems or new single-procesor netbooks. On UP and small MP systems, the wastage is insignificant. Signed-off-by: Keir Fraser <keir@xen.org> diff -r 1515484353c6 xen/arch/x86/smpboot.c --- a/xen/arch/x86/smpboot.c Thu Oct 13 10:09:28 2011 +0200 +++ b/xen/arch/x86/smpboot.c Thu Oct 13 10:25:01 2011 +0100 @@ -640,21 +640,16 @@ static void cpu_smpboot_free(unsigned in unsigned int order; order = get_order_from_pages(NR_RESERVED_GDT_PAGES); + free_xenheap_pages(per_cpu(gdt_table, cpu), order); + per_cpu(gdt_table, cpu) = NULL; + #ifdef __x86_64__ - if ( per_cpu(compat_gdt_table, cpu) ) - free_domheap_pages(virt_to_page(per_cpu(gdt_table, cpu)), order); - if ( per_cpu(gdt_table, cpu) ) - free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), - order); + free_xenheap_pages(per_cpu(compat_gdt_table, cpu), order); per_cpu(compat_gdt_table, cpu) = NULL; - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); - if ( idt_tables[cpu] ) - free_domheap_pages(virt_to_page(idt_tables[cpu]), order); -#else - free_xenheap_pages(per_cpu(gdt_table, cpu), order); - xfree(idt_tables[cpu]); #endif - per_cpu(gdt_table, cpu) = NULL; + + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t)); + free_xenheap_pages(idt_tables[cpu], order); idt_tables[cpu] = NULL; if ( stack_base[cpu] != NULL ) @@ -669,9 +664,6 @@ static int cpu_smpboot_alloc(unsigned in { unsigned int order; struct desc_struct *gdt; -#ifdef __x86_64__ - struct page_info *page; -#endif stack_base[cpu] = alloc_xenheap_pages(STACK_ORDER, 0); if ( stack_base[cpu] == NULL ) @@ -679,41 +671,28 @@ static int cpu_smpboot_alloc(unsigned in memguard_guard_stack(stack_base[cpu]); order = get_order_from_pages(NR_RESERVED_GDT_PAGES); -#ifdef __x86_64__ - page = alloc_domheap_pages(NULL, order, - MEMF_node(cpu_to_node(cpu))); - if ( !page ) + per_cpu(gdt_table, cpu) = gdt + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); + if ( gdt == NULL ) goto oom; - per_cpu(compat_gdt_table, cpu) = gdt = page_to_virt(page); - memcpy(gdt, boot_cpu_compat_gdt_table, - NR_RESERVED_GDT_PAGES * PAGE_SIZE); - gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; - page = alloc_domheap_pages(NULL, order, - MEMF_node(cpu_to_node(cpu))); - if ( !page ) - goto oom; - per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); - page = alloc_domheap_pages(NULL, order, - MEMF_node(cpu_to_node(cpu))); - if ( !page ) - goto oom; - idt_tables[cpu] = page_to_virt(page); -#else - per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); - if ( !gdt ) - goto oom; - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); - if ( idt_tables[cpu] == NULL ) - goto oom; -#endif - memcpy(gdt, boot_cpu_gdt_table, - NR_RESERVED_GDT_PAGES * PAGE_SIZE); + memcpy(gdt, boot_cpu_gdt_table, NR_RESERVED_GDT_PAGES * PAGE_SIZE); BUILD_BUG_ON(NR_CPUS > 0x10000); gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; - memcpy(idt_tables[cpu], idt_table, - IDT_ENTRIES*sizeof(idt_entry_t)); +#ifdef __x86_64__ + per_cpu(compat_gdt_table, cpu) = gdt + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); + if ( gdt == NULL ) + goto oom; + memcpy(gdt, boot_cpu_compat_gdt_table, NR_RESERVED_GDT_PAGES * PAGE_SIZE); + gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; +#endif + + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t)); + idt_tables[cpu] = alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); + if ( idt_tables[cpu] == NULL ) + goto oom; + memcpy(idt_tables[cpu], idt_table, IDT_ENTRIES * sizeof(idt_entry_t)); return 0;> Anyway, despite all this... > >> Signed-off-by: Jan Beulich <jbeulich@suse.com> > > Acked-by: Keir Fraser <keir@xen.org> > >> --- a/xen/arch/x86/smpboot.c >> +++ b/xen/arch/x86/smpboot.c >> @@ -639,9 +639,6 @@ static void cpu_smpboot_free(unsigned in >> { >> unsigned int order; >> >> - xfree(idt_tables[cpu]); >> - idt_tables[cpu] = NULL; >> - >> order = get_order_from_pages(NR_RESERVED_GDT_PAGES); >> #ifdef __x86_64__ >> if ( per_cpu(compat_gdt_table, cpu) ) >> @@ -650,10 +647,15 @@ static void cpu_smpboot_free(unsigned in >> free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), >> order); >> per_cpu(compat_gdt_table, cpu) = NULL; >> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >> + if ( idt_tables[cpu] ) >> + free_domheap_pages(virt_to_page(idt_tables[cpu]), order); >> #else >> free_xenheap_pages(per_cpu(gdt_table, cpu), order); >> + xfree(idt_tables[cpu]); >> #endif >> per_cpu(gdt_table, cpu) = NULL; >> + idt_tables[cpu] = NULL; >> >> if ( stack_base[cpu] != NULL ) >> { >> @@ -691,19 +693,25 @@ static int cpu_smpboot_alloc(unsigned in >> if ( !page ) >> goto oom; >> per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); >> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >> + page = alloc_domheap_pages(NULL, order, >> + MEMF_node(cpu_to_node(cpu))); >> + if ( !page ) >> + goto oom; >> + idt_tables[cpu] = page_to_virt(page); >> #else >> per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); >> if ( !gdt ) >> goto oom; >> + idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >> + if ( idt_tables[cpu] == NULL ) >> + goto oom; >> #endif >> memcpy(gdt, boot_cpu_gdt_table, >> NR_RESERVED_GDT_PAGES * PAGE_SIZE); >> BUILD_BUG_ON(NR_CPUS > 0x10000); >> gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; >> >> - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >> - if ( idt_tables[cpu] == NULL ) >> - goto oom; >> memcpy(idt_tables[cpu], idt_table, >> IDT_ENTRIES*sizeof(idt_entry_t)); >> >> >> >> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xensource.com >> http://lists.xensource.com/xen-devel > >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jan Beulich
2011-Oct-13 12:14 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
>>> On 13.10.11 at 11:34, Keir Fraser <keir@xen.org> wrote: > Given our antipathy to the x86-32 hypervisor, and the fact that any > remaining users of it are unlikely to be running MP systems at all let alone > large MP systems, how about this cleanup patch?... (It looks quite confusing > as a patch, actually, but does the obvious thing).Looks good to me - I was actually considering to convert the x86-64 code back to alloc_xenheap_pages() too (for we''ll need to do that eventually anyway when we want to support more than 5Tb of memory) when I put together that earlier patch, but then refrained from doing so to keep the patch size down. Jan> x86: Simplify smpboot_alloc by merging x86-{32,64} code as far as possible. > > We still need one ifdef, as x86-32 does not have a compat_gdt_table. > > On x86-32 there is 1/2-page wastage due to allocating a whole page for > the per-CPU IDT, however we expect very few users of the x86-32 > hypervisor. Those that cannot move to the 64-bit hypervisor are likely > using old single-processor systems or new single-procesor netbooks. On > UP and small MP systems, the wastage is insignificant. > > Signed-off-by: Keir Fraser <keir@xen.org> > diff -r 1515484353c6 xen/arch/x86/smpboot.c > --- a/xen/arch/x86/smpboot.c Thu Oct 13 10:09:28 2011 +0200 > +++ b/xen/arch/x86/smpboot.c Thu Oct 13 10:25:01 2011 +0100 > @@ -640,21 +640,16 @@ static void cpu_smpboot_free(unsigned in > unsigned int order; > > order = get_order_from_pages(NR_RESERVED_GDT_PAGES); > + free_xenheap_pages(per_cpu(gdt_table, cpu), order); > + per_cpu(gdt_table, cpu) = NULL; > + > #ifdef __x86_64__ > - if ( per_cpu(compat_gdt_table, cpu) ) > - free_domheap_pages(virt_to_page(per_cpu(gdt_table, cpu)), order); > - if ( per_cpu(gdt_table, cpu) ) > - free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), > - order); > + free_xenheap_pages(per_cpu(compat_gdt_table, cpu), order); > per_cpu(compat_gdt_table, cpu) = NULL; > - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); > - if ( idt_tables[cpu] ) > - free_domheap_pages(virt_to_page(idt_tables[cpu]), order); > -#else > - free_xenheap_pages(per_cpu(gdt_table, cpu), order); > - xfree(idt_tables[cpu]); > #endif > - per_cpu(gdt_table, cpu) = NULL; > + > + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t)); > + free_xenheap_pages(idt_tables[cpu], order); > idt_tables[cpu] = NULL; > > if ( stack_base[cpu] != NULL ) > @@ -669,9 +664,6 @@ static int cpu_smpboot_alloc(unsigned in > { > unsigned int order; > struct desc_struct *gdt; > -#ifdef __x86_64__ > - struct page_info *page; > -#endif > > stack_base[cpu] = alloc_xenheap_pages(STACK_ORDER, 0); > if ( stack_base[cpu] == NULL ) > @@ -679,41 +671,28 @@ static int cpu_smpboot_alloc(unsigned in > memguard_guard_stack(stack_base[cpu]); > > order = get_order_from_pages(NR_RESERVED_GDT_PAGES); > -#ifdef __x86_64__ > - page = alloc_domheap_pages(NULL, order, > - MEMF_node(cpu_to_node(cpu))); > - if ( !page ) > + per_cpu(gdt_table, cpu) = gdt > + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); > + if ( gdt == NULL ) > goto oom; > - per_cpu(compat_gdt_table, cpu) = gdt = page_to_virt(page); > - memcpy(gdt, boot_cpu_compat_gdt_table, > - NR_RESERVED_GDT_PAGES * PAGE_SIZE); > - gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; > - page = alloc_domheap_pages(NULL, order, > - MEMF_node(cpu_to_node(cpu))); > - if ( !page ) > - goto oom; > - per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); > - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); > - page = alloc_domheap_pages(NULL, order, > - MEMF_node(cpu_to_node(cpu))); > - if ( !page ) > - goto oom; > - idt_tables[cpu] = page_to_virt(page); > -#else > - per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); > - if ( !gdt ) > - goto oom; > - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); > - if ( idt_tables[cpu] == NULL ) > - goto oom; > -#endif > - memcpy(gdt, boot_cpu_gdt_table, > - NR_RESERVED_GDT_PAGES * PAGE_SIZE); > + memcpy(gdt, boot_cpu_gdt_table, NR_RESERVED_GDT_PAGES * PAGE_SIZE); > BUILD_BUG_ON(NR_CPUS > 0x10000); > gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; > > - memcpy(idt_tables[cpu], idt_table, > - IDT_ENTRIES*sizeof(idt_entry_t)); > +#ifdef __x86_64__ > + per_cpu(compat_gdt_table, cpu) = gdt > + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); > + if ( gdt == NULL ) > + goto oom; > + memcpy(gdt, boot_cpu_compat_gdt_table, NR_RESERVED_GDT_PAGES * > PAGE_SIZE); > + gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; > +#endif > + > + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t)); > + idt_tables[cpu] = alloc_xenheap_pages(order, > MEMF_node(cpu_to_node(cpu))); > + if ( idt_tables[cpu] == NULL ) > + goto oom; > + memcpy(idt_tables[cpu], idt_table, IDT_ENTRIES * sizeof(idt_entry_t)); > > return 0; > > >> Anyway, despite all this... >> >>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >> >> Acked-by: Keir Fraser <keir@xen.org> >> >>> --- a/xen/arch/x86/smpboot.c >>> +++ b/xen/arch/x86/smpboot.c >>> @@ -639,9 +639,6 @@ static void cpu_smpboot_free(unsigned in >>> { >>> unsigned int order; >>> >>> - xfree(idt_tables[cpu]); >>> - idt_tables[cpu] = NULL; >>> - >>> order = get_order_from_pages(NR_RESERVED_GDT_PAGES); >>> #ifdef __x86_64__ >>> if ( per_cpu(compat_gdt_table, cpu) ) >>> @@ -650,10 +647,15 @@ static void cpu_smpboot_free(unsigned in >>> free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), >>> order); >>> per_cpu(compat_gdt_table, cpu) = NULL; >>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >>> + if ( idt_tables[cpu] ) >>> + free_domheap_pages(virt_to_page(idt_tables[cpu]), order); >>> #else >>> free_xenheap_pages(per_cpu(gdt_table, cpu), order); >>> + xfree(idt_tables[cpu]); >>> #endif >>> per_cpu(gdt_table, cpu) = NULL; >>> + idt_tables[cpu] = NULL; >>> >>> if ( stack_base[cpu] != NULL ) >>> { >>> @@ -691,19 +693,25 @@ static int cpu_smpboot_alloc(unsigned in >>> if ( !page ) >>> goto oom; >>> per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); >>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >>> + page = alloc_domheap_pages(NULL, order, >>> + MEMF_node(cpu_to_node(cpu))); >>> + if ( !page ) >>> + goto oom; >>> + idt_tables[cpu] = page_to_virt(page); >>> #else >>> per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); >>> if ( !gdt ) >>> goto oom; >>> + idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >>> + if ( idt_tables[cpu] == NULL ) >>> + goto oom; >>> #endif >>> memcpy(gdt, boot_cpu_gdt_table, >>> NR_RESERVED_GDT_PAGES * PAGE_SIZE); >>> BUILD_BUG_ON(NR_CPUS > 0x10000); >>> gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; >>> >>> - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >>> - if ( idt_tables[cpu] == NULL ) >>> - goto oom; >>> memcpy(idt_tables[cpu], idt_table, >>> IDT_ENTRIES*sizeof(idt_entry_t)); >>> >>> >>> >>> >>> >>> _______________________________________________ >>> Xen-devel mailing list >>> Xen-devel@lists.xensource.com >>> http://lists.xensource.com/xen-devel >> >>_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2011-Oct-13 14:44 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
On 13/10/2011 13:14, "Jan Beulich" <JBeulich@suse.com> wrote:>>>> On 13.10.11 at 11:34, Keir Fraser <keir@xen.org> wrote: >> Given our antipathy to the x86-32 hypervisor, and the fact that any >> remaining users of it are unlikely to be running MP systems at all let alone >> large MP systems, how about this cleanup patch?... (It looks quite confusing >> as a patch, actually, but does the obvious thing). > > Looks good to me - I was actually considering to convert the x86-64 > code back to alloc_xenheap_pages() too (for we''ll need to do that > eventually anyway when we want to support more than 5Tb of memory) > when I put together that earlier patch, but then refrained from doing so > to keep the patch size down.You mean there''s a 5TB limit for alloc_domheap_pages() allocations?? I only switched to alloc_xenheap_pages() because it''s safe for x86-32 too... -- Keir> Jan > >> x86: Simplify smpboot_alloc by merging x86-{32,64} code as far as possible. >> >> We still need one ifdef, as x86-32 does not have a compat_gdt_table. >> >> On x86-32 there is 1/2-page wastage due to allocating a whole page for >> the per-CPU IDT, however we expect very few users of the x86-32 >> hypervisor. Those that cannot move to the 64-bit hypervisor are likely >> using old single-processor systems or new single-procesor netbooks. On >> UP and small MP systems, the wastage is insignificant. >> >> Signed-off-by: Keir Fraser <keir@xen.org> >> diff -r 1515484353c6 xen/arch/x86/smpboot.c >> --- a/xen/arch/x86/smpboot.c Thu Oct 13 10:09:28 2011 +0200 >> +++ b/xen/arch/x86/smpboot.c Thu Oct 13 10:25:01 2011 +0100 >> @@ -640,21 +640,16 @@ static void cpu_smpboot_free(unsigned in >> unsigned int order; >> >> order = get_order_from_pages(NR_RESERVED_GDT_PAGES); >> + free_xenheap_pages(per_cpu(gdt_table, cpu), order); >> + per_cpu(gdt_table, cpu) = NULL; >> + >> #ifdef __x86_64__ >> - if ( per_cpu(compat_gdt_table, cpu) ) >> - free_domheap_pages(virt_to_page(per_cpu(gdt_table, cpu)), order); >> - if ( per_cpu(gdt_table, cpu) ) >> - free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), >> - order); >> + free_xenheap_pages(per_cpu(compat_gdt_table, cpu), order); >> per_cpu(compat_gdt_table, cpu) = NULL; >> - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >> - if ( idt_tables[cpu] ) >> - free_domheap_pages(virt_to_page(idt_tables[cpu]), order); >> -#else >> - free_xenheap_pages(per_cpu(gdt_table, cpu), order); >> - xfree(idt_tables[cpu]); >> #endif >> - per_cpu(gdt_table, cpu) = NULL; >> + >> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t)); >> + free_xenheap_pages(idt_tables[cpu], order); >> idt_tables[cpu] = NULL; >> >> if ( stack_base[cpu] != NULL ) >> @@ -669,9 +664,6 @@ static int cpu_smpboot_alloc(unsigned in >> { >> unsigned int order; >> struct desc_struct *gdt; >> -#ifdef __x86_64__ >> - struct page_info *page; >> -#endif >> >> stack_base[cpu] = alloc_xenheap_pages(STACK_ORDER, 0); >> if ( stack_base[cpu] == NULL ) >> @@ -679,41 +671,28 @@ static int cpu_smpboot_alloc(unsigned in >> memguard_guard_stack(stack_base[cpu]); >> >> order = get_order_from_pages(NR_RESERVED_GDT_PAGES); >> -#ifdef __x86_64__ >> - page = alloc_domheap_pages(NULL, order, >> - MEMF_node(cpu_to_node(cpu))); >> - if ( !page ) >> + per_cpu(gdt_table, cpu) = gdt >> + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); >> + if ( gdt == NULL ) >> goto oom; >> - per_cpu(compat_gdt_table, cpu) = gdt = page_to_virt(page); >> - memcpy(gdt, boot_cpu_compat_gdt_table, >> - NR_RESERVED_GDT_PAGES * PAGE_SIZE); >> - gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; >> - page = alloc_domheap_pages(NULL, order, >> - MEMF_node(cpu_to_node(cpu))); >> - if ( !page ) >> - goto oom; >> - per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); >> - order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >> - page = alloc_domheap_pages(NULL, order, >> - MEMF_node(cpu_to_node(cpu))); >> - if ( !page ) >> - goto oom; >> - idt_tables[cpu] = page_to_virt(page); >> -#else >> - per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); >> - if ( !gdt ) >> - goto oom; >> - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >> - if ( idt_tables[cpu] == NULL ) >> - goto oom; >> -#endif >> - memcpy(gdt, boot_cpu_gdt_table, >> - NR_RESERVED_GDT_PAGES * PAGE_SIZE); >> + memcpy(gdt, boot_cpu_gdt_table, NR_RESERVED_GDT_PAGES * PAGE_SIZE); >> BUILD_BUG_ON(NR_CPUS > 0x10000); >> gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; >> >> - memcpy(idt_tables[cpu], idt_table, >> - IDT_ENTRIES*sizeof(idt_entry_t)); >> +#ifdef __x86_64__ >> + per_cpu(compat_gdt_table, cpu) = gdt >> + alloc_xenheap_pages(order, MEMF_node(cpu_to_node(cpu))); >> + if ( gdt == NULL ) >> + goto oom; >> + memcpy(gdt, boot_cpu_compat_gdt_table, NR_RESERVED_GDT_PAGES * >> PAGE_SIZE); >> + gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; >> +#endif >> + >> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(idt_entry_t)); >> + idt_tables[cpu] = alloc_xenheap_pages(order, >> MEMF_node(cpu_to_node(cpu))); >> + if ( idt_tables[cpu] == NULL ) >> + goto oom; >> + memcpy(idt_tables[cpu], idt_table, IDT_ENTRIES * sizeof(idt_entry_t)); >> >> return 0; >> >> >>> Anyway, despite all this... >>> >>>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >>> >>> Acked-by: Keir Fraser <keir@xen.org> >>> >>>> --- a/xen/arch/x86/smpboot.c >>>> +++ b/xen/arch/x86/smpboot.c >>>> @@ -639,9 +639,6 @@ static void cpu_smpboot_free(unsigned in >>>> { >>>> unsigned int order; >>>> >>>> - xfree(idt_tables[cpu]); >>>> - idt_tables[cpu] = NULL; >>>> - >>>> order = get_order_from_pages(NR_RESERVED_GDT_PAGES); >>>> #ifdef __x86_64__ >>>> if ( per_cpu(compat_gdt_table, cpu) ) >>>> @@ -650,10 +647,15 @@ static void cpu_smpboot_free(unsigned in >>>> free_domheap_pages(virt_to_page(per_cpu(compat_gdt_table, cpu)), >>>> order); >>>> per_cpu(compat_gdt_table, cpu) = NULL; >>>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >>>> + if ( idt_tables[cpu] ) >>>> + free_domheap_pages(virt_to_page(idt_tables[cpu]), order); >>>> #else >>>> free_xenheap_pages(per_cpu(gdt_table, cpu), order); >>>> + xfree(idt_tables[cpu]); >>>> #endif >>>> per_cpu(gdt_table, cpu) = NULL; >>>> + idt_tables[cpu] = NULL; >>>> >>>> if ( stack_base[cpu] != NULL ) >>>> { >>>> @@ -691,19 +693,25 @@ static int cpu_smpboot_alloc(unsigned in >>>> if ( !page ) >>>> goto oom; >>>> per_cpu(gdt_table, cpu) = gdt = page_to_virt(page); >>>> + order = get_order_from_bytes(IDT_ENTRIES * sizeof(**idt_tables)); >>>> + page = alloc_domheap_pages(NULL, order, >>>> + MEMF_node(cpu_to_node(cpu))); >>>> + if ( !page ) >>>> + goto oom; >>>> + idt_tables[cpu] = page_to_virt(page); >>>> #else >>>> per_cpu(gdt_table, cpu) = gdt = alloc_xenheap_pages(order, 0); >>>> if ( !gdt ) >>>> goto oom; >>>> + idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >>>> + if ( idt_tables[cpu] == NULL ) >>>> + goto oom; >>>> #endif >>>> memcpy(gdt, boot_cpu_gdt_table, >>>> NR_RESERVED_GDT_PAGES * PAGE_SIZE); >>>> BUILD_BUG_ON(NR_CPUS > 0x10000); >>>> gdt[PER_CPU_GDT_ENTRY - FIRST_RESERVED_GDT_ENTRY].a = cpu; >>>> >>>> - idt_tables[cpu] = xmalloc_array(idt_entry_t, IDT_ENTRIES); >>>> - if ( idt_tables[cpu] == NULL ) >>>> - goto oom; >>>> memcpy(idt_tables[cpu], idt_table, >>>> IDT_ENTRIES*sizeof(idt_entry_t)); >>>> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Xen-devel mailing list >>>> Xen-devel@lists.xensource.com >>>> http://lists.xensource.com/xen-devel >>> >>> > >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jan Beulich
2011-Oct-13 15:16 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
>>> On 13.10.11 at 16:44, Keir Fraser <keir.xen@gmail.com> wrote: > On 13/10/2011 13:14, "Jan Beulich" <JBeulich@suse.com> wrote: > >>>>> On 13.10.11 at 11:34, Keir Fraser <keir@xen.org> wrote: >>> Given our antipathy to the x86-32 hypervisor, and the fact that any >>> remaining users of it are unlikely to be running MP systems at all let alone >>> large MP systems, how about this cleanup patch?... (It looks quite confusing >>> as a patch, actually, but does the obvious thing). >> >> Looks good to me - I was actually considering to convert the x86-64 >> code back to alloc_xenheap_pages() too (for we''ll need to do that >> eventually anyway when we want to support more than 5Tb of memory) >> when I put together that earlier patch, but then refrained from doing so >> to keep the patch size down. > > You mean there''s a 5TB limit for alloc_domheap_pages() allocations??No, I mean that currently we can''t use more than 5Tb on any system. Due to address space limitations, going beyond that will require to introduce split domain and Xen heaps (including map_domain_page() etc) and hence the consistent use of alloc_xenheap_pages() vs. alloc_domheap_pages() (which currently isn''t the case - you fixed just one group of them). Remember talking about that on the summit?> I only switched to alloc_xenheap_pages() because it''s safe for x86-32 too...Sure, I just wanted to point out that this needs to be done at some point anyway. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2011-Oct-13 15:23 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
On 13/10/2011 16:16, "Jan Beulich" <JBeulich@suse.com> wrote:>>> Looks good to me - I was actually considering to convert the x86-64 >>> code back to alloc_xenheap_pages() too (for we''ll need to do that >>> eventually anyway when we want to support more than 5Tb of memory) >>> when I put together that earlier patch, but then refrained from doing so >>> to keep the patch size down. >> >> You mean there''s a 5TB limit for alloc_domheap_pages() allocations?? > > No, I mean that currently we can''t use more than 5Tb on any system. > Due to address space limitations, going beyond that will require to > introduce split domain and Xen heaps (including map_domain_page() etc) > and hence the consistent use of alloc_xenheap_pages() vs. > alloc_domheap_pages() (which currently isn''t the case - you fixed just > one group of them). Remember talking about that on the summit?Ah yes, I do remember now! K. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-Oct-13 18:36 UTC
Re: [Xen-devel] [PATCH] x86-64: don''t use xmalloc_array() for allocation of the (per-CPU) IDTs
On Thu, Oct 13, 2011 at 09:15:41AM +0100, Keir Fraser wrote:> On 13/10/2011 08:55, "Jan Beulich" <JBeulich@suse.com> wrote: > > >>>> On 13.10.11 at 09:50, Keir Fraser <keir@xen.org> wrote: > >> Finally, I''m not sure about more x86-64 code movement: I''d like to kill > >> x86-32 entirely really. > > > > I know, but you got pushed back each time you tried... > > I think we''re stuck with it for 4.2. Will try again when we open development > for 4.3. The argument last time was the low-powered Atoms, used in low-end > netbooks; but there''s no evidence that anyone is using Xen on such > platforms. I can''t imagine it would be very worthwhile.I''ve actually been using Xen 4.1.1 on them. But the Atom I''ve is 64-bit capable. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel