>From: Alex Williamson >Sent: 2006年5月22日 6:30 > >On Sun, 2006-05-21 at 15:07 -0600, Alex Williamson wrote: >> diff -r 4dcb93547710 tools/python/xen/xend/image.py >> --- a/tools/python/xen/xend/image.py Sun May 21 09:55:15 2006 >+0100 >> +++ b/tools/python/xen/xend/image.py Sun May 21 14:25:19 2006 >-0600 >> @@ -146,7 +146,7 @@ class ImageHandler: >> """@return The memory required, in KiB, by the domain to >store the >> given amount, also in KiB. This is normally just mem, but if >HVM is >> supported, keep a little extra free.""" >> - if ''hvm'' in xc.xeninfo()[''xen_caps'']: >> + if ''hvm'' in xc.xeninfo()[''xen_caps''] and os.uname()[4] !>''ia64'': >> mem_kb += 4*1024; >> return mem_kb > > Looks like this is just a partial solution, VTi guests are still >broken with only this change. Instead, we probably need to look at cset >10040. I suspect we don''t yet have the ballooning support and need to >do the allocation up front. Thanks, > > AlexWe just need to reverse the whole change for ia64, since both domU and domVTI are insert a hole by this auto-balloon patch. Due to missing balloon support on xen/ia64 as you said, both domU and domVTI failed due to this change. Patch attached. Thanks, Kevin _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 22 May 2006, at 10:06, Tian, Kevin wrote:> We just need to reverse the whole change for ia64, since both domU > and domVTI are insert a hole by this auto-balloon patch. Due to > missing balloon support on xen/ia64 as you said, both domU and domVTI > failed due to this change.The first patch that you work around seems okay to me. That is, it seems correct that we make initial reservation exclude ''getDomainMemory headroom''. Shouldn''t ia64 reserve extra memory as it needs it, as x86 does, rather than up front? The second bit of your workaround, which applies to getDomainMemory: I''ll wait and see if Charles has anything to say, but otherwise I''ll remove the code that adds the extra slack entirely. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2006-May-22 09:50 UTC
[Xen-ia64-devel] Re: [Xen-devel] Re: [PATCH] Disable auto-balloon on ia64
On 22 May 2006, at 10:37, Keir Fraser wrote:>> We just need to reverse the whole change for ia64, since both domU >> and domVTI are insert a hole by this auto-balloon patch. Due to >> missing balloon support on xen/ia64 as you said, both domU and domVTI >> failed due to this change. > > The first patch that you work around seems okay to me. That is, it > seems correct that we make initial reservation exclude > ''getDomainMemory headroom''. Shouldn''t ia64 reserve extra memory as it > needs it, as x86 does, rather than up front? > > The second bit of your workaround, which applies to getDomainMemory: > I''ll wait and see if Charles has anything to say, but otherwise I''ll > remove the code that adds the extra slack entirely.Thinking about it, that slack might have been added to give enough space for shadow page tables for live migration. Also, it shouldn''t give you any problems if you weren''t allocating headroom up front -- if you can fix ia64 to allocate the extra memory as needed then you shouldn''t need either of your workarounds? -- Keir _______________________________________________ Xen-ia64-devel mailing list Xen-ia64-devel@lists.xensource.com http://lists.xensource.com/xen-ia64-devel
>From: Keir Fraser [mailto:Keir.Fraser@cl.cam.ac.uk] >Sent: 2006年5月22日 17:37 >On 22 May 2006, at 10:06, Tian, Kevin wrote: > >> We just need to reverse the whole change for ia64, since both >domU >> and domVTI are insert a hole by this auto-balloon patch. Due to >> missing balloon support on xen/ia64 as you said, both domU and >domVTI >> failed due to this change. > >The first patch that you work around seems okay to me. That is, it >seems correct that we make initial reservation exclude >''getDomainMemory >headroom''. Shouldn''t ia64 reserve extra memory as it needs it, as x86 >does, rather than up front?I have to admit that currently xen/ia64 hasn''t enough sanity check about reserving extra memory, which should be changed once balloon feature is added. Then same policy whatever is applicable can be added to ia64. Now ia64 dom0 has been changed to vp model (p!=m) by Isaku, and thus balloon can be foreseeable soon. In currently stage, we can just ensure ia64 working by ensuring all max_pages frames are allocated without empty holes.> >The second bit of your workaround, which applies to getDomainMemory: >I''ll wait and see if Charles has anything to say, but otherwise I''ll >remove the code that adds the extra slack entirely. > > -- KeirYes, let''s see whether Charles has other good reason for that change. :-) Thanks, Kevin _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Charles Coffing
2006-May-22 15:12 UTC
[Xen-devel] Overcommitting memory (was: Disable auto-balloon on ia64)
>>> On Mon, May 22, 2006 at 3:37 AM, in message<de6a6f8a49c55295ad1cedb0718099ef@cl.cam.ac.uk>, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:> On 22 May 2006, at 10:06, Tian, Kevin wrote: > >> We just need to reverse the whole change for ia64, since bothdomU>> and domVTI are insert a hole by this auto- balloon patch. Due to >> missing balloon support on xen/ia64 as you said, both domU anddomVTI>> failed due to this change. > > The first patch that you work around seems okay to me. That is, it > seems correct that we make initial reservation exclude''getDomainMemory> headroom''. Shouldn''t ia64 reserve extra memory as it needs it, as x86> does, rather than up front? > > The second bit of your workaround, which applies to getDomainMemory:> I''ll wait and see if Charles has anything to say, but otherwise I''ll> remove the code that adds the extra slack entirely.I think we have a more general problem here. Xen, historically, hasn''t overcommitted memory. But with shadow page tables and HVM, that''s not really true, is it? Suppose I start up a 256 MB HVM domain running, say, a forking web server. How much physical RAM does this take? Depends on the load, doesn''t it? Unless I''m missing something, there is no "big enough" amount of slack, if you care about reliability. With Yunhong''s BUG -> domain_crash patch, the box shouldn''t crash, but the domain still might. In shadow32.c, I see a FIXME comment that refers to "shadow flush". Even if such things are done, can you put an upper limit on the runtime memory overhead for an HVM domain? _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2006-May-22 15:17 UTC
[Xen-devel] Re: Overcommitting memory (was: Disable auto-balloon on ia64)
On 22 May 2006, at 16:12, Charles Coffing wrote:> In shadow32.c, I see a FIXME comment that refers to "shadow flush". > Even if such things are done, can you put an upper limit on the runtime > memory overhead for an HVM domain?Yes, it ought to be a space/time tradeoff. The shadow pagetables should be regarded merely as a cache. However, the current shadow mode''s memory handling sucks. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel