Keshav Darak
2011-Mar-20 22:34 UTC
[Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
We have implemented hugepage support for guests in following manner
In
our implementation we added a parameter hugepage_num which is specified
in the config file of the DomU. It is the number of hugepages that the
guest is guaranteed to receive whenever the kernel asks for hugepage by
using its boot time parameter or reserving after booting (eg. Using echo
XX > /proc/sys/vm/nr_hugepages). During creation of the domain we
reserve MFN''s for these hugepages and store them in the list. The
listhead of this list is inside the domain structure with name
"hugepage_list". When the domain is booting, at that time the memory
seen by the kernel is allocated memory less the amount required for hugepages.
The function
reserve_hugepage_range is called as a initcall. Before this function the
xen_extra_mem_start points to this apparent end of the memory. In this
function we reserve the PFN range for the hugepages which are going to
be allocated by kernel by incrementing the xen_extra_mem_start. We
maintain these PFNs as pages in "xen_hugepfn_list" in the kernel.
Now
before the kernel requests for hugepages, it makes a hypercall
HYPERVISOR_memory_op to get count of hugepages allocated to it and
accordingly reserves the pfn range.
then whenever kernel requests for
hugepages it again make hypercall HYPERVISOR_memory_op to get the
preallocated hugepage and according makes the p2m mapping on both sides
(xen as well as kernel side)
The approach can be better explained using the presentation attached.
--
Keshav Darak
Kaustubh Kabra
Ashwin Vasani
Aditya Gadre
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
Keshav Darak
2011-Mar-21 21:01 UTC
Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
have corrected few mistakes in previously attached xen patch file.
Please review it.
--- On Sun, 3/20/11, Keshav Darak <keshav_darak@yahoo.com> wrote:
From: Keshav Darak <keshav_darak@yahoo.com>
Subject: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
To: xen-devel@lists.xensource.com
Cc: jeremy@goop.org, keir@xen.org
Date: Sunday, March 20, 2011, 10:34 PM
We have implemented hugepage support for guests in following manner
In
our implementation we added a parameter hugepage_num which is specified
in the config file of the DomU. It is the number of hugepages that the
guest is guaranteed to receive whenever the kernel asks for hugepage by
using its boot time parameter or reserving after booting (eg. Using echo
XX > /proc/sys/vm/nr_hugepages). During creation of the domain we
reserve MFN''s for these hugepages and store them in the list. The
listhead of this list is inside the domain structure with name
"hugepage_list". When the domain is booting, at that time the memory
seen by the kernel is allocated memory less the amount required for hugepages.
The function
reserve_hugepage_range is called as a initcall. Before this function the
xen_extra_mem_start points to this apparent end of the memory. In this
function we reserve the PFN range for the hugepages which are going to
be allocated by kernel by incrementing the xen_extra_mem_start. We
maintain these PFNs as pages in "xen_hugepfn_list" in the kernel.
Now
before the kernel requests for hugepages, it makes a hypercall
HYPERVISOR_memory_op to get count of hugepages allocated to it and
accordingly reserves the pfn range.
then whenever kernel requests for
hugepages it again make hypercall HYPERVISOR_memory_op to get the
preallocated hugepage and according makes the p2m mapping on both sides
(xen as well as kernel side)
The approach can be better explained using the presentation attached.
--
Keshav Darak
Kaustubh Kabra
Ashwin Vasani
Aditya Gadre
-----Inline Attachment Follows-----
_______________________________________________
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-Mar-21 21:31 UTC
Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
Keshav, There is already optional support for superpage allocations and mappings for PV guests in the hypervisor and toolstack. See the opt_allow_superpages boolean flag in the hypervisor, and the ''superpages'' domain config option that can be specified when creating a new domain via xend/xm. -- Keir On 21/03/2011 21:01, "Keshav Darak" <keshav_darak@yahoo.com> wrote:> have corrected few mistakes in previously attached xen patch file. > Please review it. > > --- On Sun, 3/20/11, Keshav Darak <keshav_darak@yahoo.com> wrote: >> >> From: Keshav Darak <keshav_darak@yahoo.com> >> Subject: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB >> pages >> To: xen-devel@lists.xensource.com >> Cc: jeremy@goop.org, keir@xen.org >> Date: Sunday, March 20, 2011, 10:34 PM >> >> We have implemented hugepage support for guests in following manner >> >> In our implementation we added a parameter hugepage_num which is specified in >> the config file of the DomU. It is the number of hugepages that the guest is >> guaranteed to receive whenever the kernel asks for hugepage by using its boot >> time parameter or reserving after booting (eg. Using echo XX > >> /proc/sys/vm/nr_hugepages). During creation of the domain we reserve MFN''s >> for these hugepages and store them in the list. The listhead of this list is >> inside the domain structure with name "hugepage_list". When the domain is >> booting, at that time the memory seen by the kernel is allocated memory less >> the amount required for hugepages. The function reserve_hugepage_range is >> called as a initcall. Before this function the xen_extra_mem_start points to >> this apparent end of the memory. In this function we reserve the PFN range >> for the hugepages which are going to be allocated by kernel by incrementing >> the xen_extra_mem_start. We maintain these PFNs as pages in >> "xen_hugepfn_list" in the kernel. >> >> Now before the kernel requests for hugepages, it makes a hypercall >> HYPERVISOR_memory_op to get count of hugepages allocated to it and >> accordingly reserves the pfn range. >> then whenever kernel requests for hugepages it again make hypercall >> HYPERVISOR_memory_op to get the preallocated hugepage and according makes the >> p2m mapping on both sides (xen as well as kernel side) >> >> The approach can be better explained using the presentation attached. >> >> -- >> Keshav Darak >> Kaustubh Kabra >> Ashwin Vasani >> Aditya Gadre >> >> >> >> -----Inline Attachment Follows----- >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xensource.com </mc/compose?to=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
Keshav Darak
2011-Mar-22 12:36 UTC
Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
Keir, We are aware of it and we have to use ''opt_allow_superpages'' boolean flag in our implementation too. But when we use superpages flag in domain configuration file, entire domain boots on hugepages (superpages).If the specified memory in ''hugepages'' for the domain is not available, then the domain does not boot. But in our implementation , we target to give only those many hugepages ( using "hugepage_num" option in config file) to the domain that it actually requires and hence entire domain need not be booted on hugepages. This is to support domains that boot with 4 KB pages and still can use hugepages. So, the pressure on the number of hugepages required for a domain even to boot is reduced to a great extent. --- On Mon, 3/21/11, Keir Fraser <keir.xen@gmail.com> wrote: From: Keir Fraser <keir.xen@gmail.com> Subject: Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages To: "Keshav Darak" <keshav_darak@yahoo.com>, xen-devel@lists.xensource.com Cc: jeremy@goop.org Date: Monday, March 21, 2011, 9:31 PM Keshav, There is already optional support for superpage allocations and mappings for PV guests in the hypervisor and toolstack. See the opt_allow_superpages boolean flag in the hypervisor, and the ''superpages'' domain config option that can be specified when creating a new domain via xend/xm. -- Keir On 21/03/2011 21:01, "Keshav Darak" <keshav_darak@yahoo.com> wrote:> have corrected few mistakes in previously attached xen patch file. > Please review it. > > --- On Sun, 3/20/11, Keshav Darak <keshav_darak@yahoo.com> wrote: >> >> From: Keshav Darak <keshav_darak@yahoo.com> >> Subject: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB >> pages >> To: xen-devel@lists.xensource.com >> Cc: jeremy@goop.org, keir@xen.org >> Date: Sunday, March 20, 2011, 10:34 PM >> >> We have implemented hugepage support for guests in following manner >> >> In our implementation we added a parameter hugepage_num which is specified in >> the config file of the DomU. It is the number of hugepages that the guest is >> guaranteed to receive whenever the kernel asks for hugepage by using its boot >> time parameter or reserving after booting (eg. Using echo XX > >> /proc/sys/vm/nr_hugepages). During creation of the domain we reserve MFN''s >> for these hugepages and store them in the list. The listhead of this list is >> inside the domain structure with name "hugepage_list". When the domain is >> booting, at that time the memory seen by the kernel is allocated memory less >> the amount required for hugepages. The function reserve_hugepage_range is >> called as a initcall. Before this function the xen_extra_mem_start points to >> this apparent end of the memory. In this function we reserve the PFN range >> for the hugepages which are going to be allocated by kernel by incrementing >> the xen_extra_mem_start. We maintain these PFNs as pages in >> "xen_hugepfn_list" in the kernel. >> >> Now before the kernel requests for hugepages, it makes a hypercall >> HYPERVISOR_memory_op to get count of hugepages allocated to it and >> accordingly reserves the pfn range. >> then whenever kernel requests for hugepages it again make hypercall >> HYPERVISOR_memory_op to get the preallocated hugepage and according makes the >> p2m mapping on both sides (xen as well as kernel side) >> >> The approach can be better explained using the presentation attached. >> >> -- >> Keshav Darak >> Kaustubh Kabra >> Ashwin Vasani >> Aditya Gadre >> >> >> >> -----Inline Attachment Follows----- >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@lists.xensource.com </mc/compose?to=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-Mar-22 14:07 UTC
Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
On 22/03/2011 12:36, "Keshav Darak" <keshav_darak@yahoo.com> wrote:> Keir, > We are aware of it and we have to use ''opt_allow_superpages'' boolean flag > in our implementation too. But when we use superpages flag in domain > configuration file, > entire domain boots on hugepages (superpages).If the specified memory in > ''hugepages'' for the domain is not available, then the domain does not boot. > But in our implementation , we target to give only those many hugepages ( > using "hugepage_num" option in config file) to the domain that it actually > requires and hence entire domain need not be booted on hugepages. > This is to support domains that boot with 4 KB pages and still can use > hugepages. So, > the pressure on the number of hugepages required for a domain even to boot is > reduced to a great extent.Okay, I don''t see why that would need further changes in the hypervisor itself, however. -- Keir> --- On Mon, 3/21/11, Keir Fraser <keir.xen@gmail.com> wrote: >> >> From: Keir Fraser <keir.xen@gmail.com> >> Subject: Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB >> pages >> To: "Keshav Darak" <keshav_darak@yahoo.com>, xen-devel@lists.xensource.com >> Cc: jeremy@goop.org >> Date: Monday, March 21, 2011, 9:31 PM >> >> Keshav, >> >> There is already optional support for superpage allocations and mappings for >> PV guests in the hypervisor and toolstack. See the opt_allow_superpages >> boolean flag in the hypervisor, and the ''superpages'' domain config option >> that can be specified when creating a new domain via xend/xm. >> >> -- Keir >> >> On 21/03/2011 21:01, "Keshav Darak" <keshav_darak@yahoo.com >> </mc/compose?to=keshav_darak@yahoo.com> > wrote: >> >>> have corrected few mistakes in previously attached xen patch file. >>> Please review it. >>> >>> --- On Sun, 3/20/11, Keshav Darak <keshav_darak@yahoo.com >>> </mc/compose?to=keshav_darak@yahoo.com> > wrote: >>>> >>>> From: Keshav Darak <keshav_darak@yahoo.com >>>> </mc/compose?to=keshav_darak@yahoo.com> > >>>> Subject: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB >>>> pages >>>> To: xen-devel@lists.xensource.com >>>> </mc/compose?to=xen-devel@lists.xensource.com> >>>> Cc: jeremy@goop.org </mc/compose?to=jeremy@goop.org> , keir@xen.org >>>> </mc/compose?to=keir@xen.org> >>>> Date: Sunday, March 20, 2011, 10:34 PM >>>> >>>> We have implemented hugepage support for guests in following manner >>>> >>>> In our implementation we added a parameter hugepage_num which is specified >>>> in >>>> the config file of the DomU. It is the number of hugepages that the guest >>>> is >>>> guaranteed to receive whenever the kernel asks for hugepage by using its >>>> boot >>>> time parameter or reserving after booting (eg. Using echo XX > >>>> /proc/sys/vm/nr_hugepages). During creation of the domain we reserve MFN''s >>>> for these hugepages and store them in the list. The listhead of this list >>>> is >>>> inside the domain structure with name "hugepage_list". When the domain is >>>> booting, at that time the memory seen by the kernel is allocated memory >>>> less >>>> the amount required for hugepages. The function reserve_hugepage_range is >>>> called as a initcall. Before this function the xen_extra_mem_start points >>>> to >>>> this apparent end of the memory. In this function we reserve the PFN range >>>> for the hugepages which are going to be allocated by kernel by incrementing >>>> the xen_extra_mem_start. We maintain these PFNs as pages in >>>> "xen_hugepfn_list" in the kernel. >>>> >>>> Now before the kernel requests for hugepages, it makes a hypercall >>>> HYPERVISOR_memory_op to get count of hugepages allocated to it and >>>> accordingly reserves the pfn range. >>>> then whenever kernel requests for hugepages it again make hypercall >>>> HYPERVISOR_memory_op to get the preallocated hugepage and according makes >>>> the >>>> p2m mapping on both sides (xen as well as kernel side) >>>> >>>> The approach can be better explained using the presentation attached. >>>> >>>> -- >>>> Keshav Darak >>>> Kaustubh Kabra >>>> Ashwin Vasani >>>> Aditya Gadre >>>> >>>> >>>> >>>> -----Inline Attachment Follows----- >>>> >>>> _______________________________________________ >>>> Xen-devel mailing list >>>> Xen-devel@lists.xensource.com >>>> </mc/compose?to=Xen-devel@lists.xensource.com> >>>> </mc/compose?to=Xen-devel@lists.xensource.com >>>> </mc/compose?to=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
Konrad Rzeszutek Wilk
2011-Mar-22 16:49 UTC
Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
On Sun, Mar 20, 2011 at 03:34:51PM -0700, Keshav Darak wrote:> We have implemented hugepage support for guests in following manner > > In > our implementation we added a parameter hugepage_num which is specified > in the config file of the DomU. It is the number of hugepages that the > guest is guaranteed to receive whenever the kernel asks for hugepage by > using its boot time parameter or reserving after booting (eg. Using echo > XX > /proc/sys/vm/nr_hugepages). During creation of the domain we > reserve MFN''s for these hugepages and store them in the list. TheThere is bootup option for normal Linux kernels to set that up. Was that something you could use? In regards to the patch, I''ve some questions..>diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h >index bf88684..7707e21 100644 >--- a/arch/x86/include/asm/hugetlb.h >+++ b/arch/x86/include/asm/hugetlb.h >@@ -98,6 +98,14 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma, > > return changed; > } >+#ifdef CONFIG_XEN >+struct page* allocate_hugepage(int); >+#else >+static inline struct page * allocate_hugepage(int order) >+{ >+ return NULL; >+} >+#endifSo it looks like you are exposing the allocate_hugepage to be out of the hotplug memory. Could you do this via a pvops structure instead? You should also seperate this functionality as its own patch - ie, expose the allocate_hugepage.> > static inline int arch_prepare_hugepage(struct page *page) > { >index f46c340..00c489a 100644 >--- a/arch/x86/mm/hugetlbpage.c >+++ b/arch/x86/mm/hugetlbpage.c >@@ -147,8 +147,7 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, > pte = (pte_t *) pmd_alloc(mm, pud, addr); > } > } >- BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); >- >+ BUG_ON(pte && !pte_none(*pte) && !((*pte).pte & (_AT(pteval_t, 1)<<7)));Ugh. That is horrible. why can''t you use ''pte_huge'' ? Is it b/c of this * (We should never see kernel mappings with _PAGE_PSE set, * but we could see hugetlbfs mappings, I think.). */ if (pat_enabled && !WARN_ON(pte & _PAGE_PAT)) { in xen/mmu.c? If so, have you thought about removing the warnings and/or changing the logic there instead?> return pte; > } > >diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c >index 070f138..c1db610 100644 >--- a/arch/x86/xen/enlighten.c >+++ b/arch/x86/xen/enlighten.c >@@ -58,6 +58,7 @@ > #include <asm/reboot.h> > #include <asm/stackprotector.h> > #include <asm/hypervisor.h> >+#include <linux/list.h> > > #include "xen-ops.h" > #include "mmu.h" >@@ -76,6 +77,9 @@ EXPORT_SYMBOL(machine_to_phys_mapping); > unsigned int machine_to_phys_order; > EXPORT_SYMBOL(machine_to_phys_order); > >+struct list_head xen_hugepfn_list; >+EXPORT_SYMBOL_GPL(xen_hugepfn_list); >+Hmm, a list, but no locking? There is no need for a spinlock?> struct start_info *xen_start_info; > EXPORT_SYMBOL_GPL(xen_start_info); > >diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c >index 32a1c65..fa9fa6c 100644 >--- a/arch/x86/xen/mmu.c >+++ b/arch/x86/xen/mmu.c >@@ -44,6 +44,7 @@ > #include <linux/bug.h> > #include <linux/vmalloc.h> > #include <linux/module.h> >+#include <linux/bootmem.h> > > #include <asm/pgtable.h> > #include <asm/tlbflush.h> >@@ -2776,5 +2784,79 @@ static int __init xen_mmu_debugfs(void) > return 0; > } > fs_initcall(xen_mmu_debugfs); >+//a2k2 >+extern struct list_head xen_hugepfn_list; >+static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; >+ >+static void scrub_page(struct page *page) >+{ >+#ifdef CONFIG_XEN_SCRUB_PAGES >+ clear_highpage(page); >+#endifYou don''t seem to use this anywhere..>+} >+#ifdef CONFIG_HIGHMEM >+#define inc_totalhigh_pages() (totalhigh_pages++) >+#define dec_totalhigh_pages() (totalhigh_pages--)so what do you do with those? I seem incremented, but nothing seems to use them.>+#else >+#define inc_totalhigh_pages() do {} while(0) >+#define dec_totalhigh_pages() do {} while(0) >+#endif >+ >+struct page* allocate_hugepage(int order){ >+ unsigned long mfn, i, j;You seem to be definiing ''i'' but not using it?>+ struct page *page; >+ long rc,cnt;You should be using ''int'' for rc.>+ unsigned long pfn; >+ struct xen_memory_reservation reservation = { >+ .address_bits = 0, >+ .domid = DOMID_SELF >+ }; >+ if(list_empty(&xen_hugepfn_list)){ >+ return NULL; >+ } >+ page = list_entry(xen_hugepfn_list.next, struct page, lru); >+ list_del(&page->lru); >+ frame_list[0] = page_to_pfn(page); >+ >+ set_xen_guest_handle(reservation.extent_start, frame_list); >+ reservation.nr_extents = 1; >+ reservation.extent_order = 9;shouldn''t this ''order'' instead of 9''?>+ cnt=1<<order; >+ rc = HYPERVISOR_memory_op(XENMEM_populate_hugepage, &reservation); >+ if (rc <= 0) >+ { >+ printk("a2k2: could not allocate hugepage\n");Please run ''script/checkpatch.pl'' before posting. It will show that this a not good.>+ goto out1; >+ } >+ pfn=page_to_pfn(page); >+ if(rc) >+ { >+ mfn = frame_list[0]; >+ for (j = 0; j < cnt; j++, pfn++, mfn++) { >+ set_phys_to_machine(pfn, mfn); >+ if (pfn < max_low_pfn) {... and what if ''pfn > max_low_pfn'' ? What should we do then?>+ int ret; >+ ret = HYPERVISOR_update_va_mapping( >+ (unsigned long)__va(pfn << PAGE_SHIFT),Use the PFN_DOWN macro please.>+ mfn_pte(mfn, PAGE_KERNEL), >+ 0); >+ BUG_ON(ret);Ugh. what if you just stopped the allocation and returned NULL instead?>+ } >+ } >+ >+ ClearPageReserved(page); >+ atomic_set(&page->_count,1);Ugh.. Is that correct? Can you explain why you need to do that?>+ }What if rc is zero? Should we ocntinue on with page?>+ if (PageHighMem(page)) { >+ for(i=0;i<512;i++)Shouldn''t you determine the value 512 from the ''order''?>+ inc_totalhigh_pages(); >+ } >+ totalram_pages+=512;Ditto.>+ __SetPageHead(page); >+ set_compound_order(page,order); >+ return page; >+ out1:shouldn''t you return the page back on the xen_hugepfn_list?>+ return NULL; >+} > > #endif /* CONFIG_XEN_DEBUG_FS */ >diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c >index 1a1934a..c1781e7 100644 >--- a/arch/x86/xen/setup.c >+++ b/arch/x86/xen/setup.c >@@ -138,6 +138,40 @@ static unsigned long __init xen_return_unused_memory(unsigned long max_pfn, > return released; > } > >+extern struct list_head xen_hugepfn_list; >+static int __init reserve_hugepage_range(void) >+{ >+ phys_addr_t temp,hugemem_start; >+ unsigned long i,ret;Is ''unsigned long'' the right type for ''ret''?>+ struct page *page; >+ static unsigned long frame_list[1]; >+ struct xen_memory_reservation reservation = { >+ .address_bits = 0, >+ .extent_order = 0, >+ .nr_extents = 1, >+ .domid = DOMID_SELF >+ }; >+ if(!xen_pv_domain()) >+ return -ENODEV; >+ set_xen_guest_handle(reservation.extent_start, frame_list); >+ hugemem_start=PFN_UP(xen_extra_mem_start); >+ ret = HYPERVISOR_memory_op(20, &reservation);20? There is no #define for this? You are not checking to see if the hypercall failed.>+ printk("a2k2: num of hugepages found =%lu\n",ret); >+ temp=PFN_PHYS(PFN_UP(xen_extra_mem_start)+ret*512);There has to be a better way of doing this. You are assuming that the hugepage is always 2MB. What if it is 16MB? Is there a way you can use any definitions of the architecture for this?>+ >+ xen_extra_mem_start=temp; >+ xen_extra_mem_size-=ret*2*1024*1024;Ditto. You are assuming it is 2MB. I couldbe bigger (or smaller) depending on the architecture.>+ INIT_LIST_HEAD(&xen_hugepfn_list); >+ for(i=0;i<ret;i++) >+ { >+ page=pfn_to_page(hugemem_start); >+ list_add_tail(&page->lru,&xen_hugepfn_list); >+ hugemem_start+=512; >+ } >+ return 0; >+} >+subsys_initcall(reserve_hugepage_range); >+ > /** > * machine_specific_memory_setup - Hook for machine specific memory setup. > **/ >diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h >index aa4e368..168dd2b 100644 >--- a/include/xen/interface/memory.h >+++ b/include/xen/interface/memory.h >@@ -19,6 +19,7 @@ > #define XENMEM_increase_reservation 0 > #define XENMEM_decrease_reservation 1 > #define XENMEM_populate_physmap 6 >+#define XENMEM_populate_hugepage 19 > struct xen_memory_reservation { > > /* >diff --git a/mm/hugetlb.c b/mm/hugetlb.c >index f5a106e..7e38f73 100644 >--- a/mm/hugetlb.c >+++ b/mm/hugetlb.c >@@ -18,6 +18,7 @@ > #include <linux/mutex.h> > #include <linux/bootmem.h> > #include <linux/sysfs.h> >+#include <xen/xen.h> > > #include <asm/page.h> > #include <asm/pgtable.h> >@@ -600,17 +620,19 @@ int PageHuge(struct page *page) > return dtor == free_huge_page; > } > >+ > static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) > { > struct page *page; >- > if (h->order >= MAX_ORDER) > return NULL; >- >- page = alloc_pages_exact_node(nid, >- htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| >- __GFP_REPEAT|__GFP_NOWARN, >- huge_page_order(h)); >+ if(!xen_pv_domain())Ugh. That is not the right way. You should be looking at using the pvops struct interface so that you can over-write the baremetal default implementation.>+ page = alloc_pages_exact_node(nid, >+ htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| >+ __GFP_REPEAT|__GFP_NOWARN, >+ huge_page_order(h)); >+ else >+ page=allocate_hugepage(huge_page_order(h)); > if (page) { > if (arch_prepare_hugepage(page)) { > __free_pages(page, huge_page_order(h)); >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keshav Darak
2011-Mar-22 18:05 UTC
Re: [Xen-devel] PATCH: Hugepage support for Domains booting with 4KB pages
Konrad, Thanks for reviewing the patch.>> We have implemented hugepage support for guests in following manner >> >> In >> our implementation we added a parameter hugepage_num which is specified >> in the config file of the DomU. It is the number of hugepages that the >> guest is guaranteed to receive whenever the kernel asks for hugepage by >> using its boot time parameter or reserving after booting (eg. Using echo >> XX > /proc/sys/vm/nr_hugepages). During creation of the domain we >> reserve MFN''s for these hugepages and store them in the list. The>There is bootup option for normal Linux kernels to set that up. Was >that something you could use?ya, it can be used too, to allocate the hugepages.>> >> static inline int arch_prepare_hugepage(struct page *page) >> { >>index f46c340..00c489a 100644 >>--- a/arch/x86/mm/hugetlbpage.c >>+++ b/arch/x86/mm/hugetlbpage.c >>@@ -147,8 +147,7 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, >> pte = (pte_t *) pmd_alloc(mm, pud, addr); >> } >> } >>- BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); >>- >>+ BUG_ON(pte && !pte_none(*pte) && !((*pte).pte & (_AT(pteval_t, 1)<<7)));>Ugh. That is horrible.>why can''t you use ''pte_huge'' ? Is it b/c of this > * (We should never see kernel mappings with _PAGE_PSE set, > * but we could see hugetlbfs mappings, I think.). > */Here actually we don''t known the exact reason, but when pte_huge was used the BUG_ON was called even though the PSE bit was set, so we had to rewrite the BUG_ON testing the 7th bit.there could be better ways to do it, But we couldn''t find the exact reasons why was it(pte_huge) returning 0 even when the pte was a huge_pte. we will try to resolve other issues with the patch as soon as possible. -- Keshav Darak Kaustubh Kabra Ashwin Vasani Aditya Gadre _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel