MaoXiaoyun
2011-Mar-04 11:11 UTC
[Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
Hi:
I''ve been testing on memory overcommit on Xen by using balloon
driver.
On our stress test, it is possilbe that heap memory in xen is use up. Thus the
serial
port will show log as below:
(XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages
(XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages
(XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages
I am asking is it harmfull to domain?
If so, I might need find a way to reserve some memory for xen, which looks
kinds of difficult.
Thanks.
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Tim Deegan
2011-Mar-04 11:16 UTC
Re: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
At 11:11 +0000 on 04 Mar (1299237101), MaoXiaoyun wrote:> Hi: > > I''ve been testing on memory overcommit on Xen by using balloon driver. > On our stress test, it is possilbe that heap memory in xen is use up. Thus the serial > port will show log as below: > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > I am asking is it harmfull to domain?It means that the log-dirty code wasn''t able to extend its bitmap and callers have to assume that all pages are dirty. It''s bad for performance but should be OK. If you rebase to the latest 4.1 RC, this particular message should go away as log-dirty bitmaps are no longer pulled from common memory.> If so, I might need find a way to reserve some memory for xen, which looks > kinds of difficult.I think you might find you need to do this anyway - there are other dynamic allocations in Xen which might not fail so gracefully (in particular around setting up new domains). Tim. -- Tim Deegan <Tim.Deegan@citrix.com> Principal Software Engineer, Xen Platform Team Citrix Systems UK Ltd. (Company #02937203, SL9 0BG) _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
MaoXiaoyun
2011-Mar-07 03:41 UTC
RE: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
Thanks Tim. Do you have suggestion on how many memory I should reserved, is 512M enough? There is a balloon daemon process in dom0 do the memory management, the striaght way to reserve memory is after recycle memory form domains which no need memory , then give the memory to those domains who need memory. What do you think of this?> Date: Fri, 4 Mar 2011 11:16:59 +0000 > From: Tim.Deegan@citrix.com > To: tinnycloud@hotmail.com > CC: xen-devel@lists.xensource.com > Subject: Re: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull? > > At 11:11 +0000 on 04 Mar (1299237101), MaoXiaoyun wrote: > > Hi: > > > > I''ve been testing on memory overcommit on Xen by using balloon driver. > > On our stress test, it is possilbe that heap memory in xen is use up. Thus the serial > > port will show log as below: > > > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > > > I am asking is it harmfull to domain? > > It means that the log-dirty code wasn''t able to extend its bitmap and > callers have to assume that all pages are dirty. It''s bad for > performance but should be OK. > > If you rebase to the latest 4.1 RC, this particular message should go > away as log-dirty bitmaps are no longer pulled from common memory. > > > If so, I might need find a way to reserve some memory for xen, which looks > > kinds of difficult. > > I think you might find you need to do this anyway - there are other > dynamic allocations in Xen which might not fail so gracefully (in > particular around setting up new domains). > > Tim. > > -- > Tim Deegan <Tim.Deegan@citrix.com> > Principal Software Engineer, Xen Platform Team > Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Tim Deegan
2011-Mar-07 09:04 UTC
Re: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
At 03:41 +0000 on 07 Mar (1299469316), MaoXiaoyun wrote:> Thanks Tim. > > Do you have suggestion on how many memory I should reserved, is 512M > enough? There is a balloon daemon process in dom0 do the memory > management, the striaght way to reserve memory is after recycle memory > form domains which no need memory , then give the memory to those > domains who need memory. What do you think of this?Maybe the people who have been working on the toolstack can answer this one - 512MiB free sounds like more than enough to me but I could be wrong. Tim.> > Date: Fri, 4 Mar 2011 11:16:59 +0000 > > From: Tim.Deegan@citrix.com > > To: tinnycloud@hotmail.com > > CC: xen-devel@lists.xensource.com > > Subject: Re: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull? > > > > At 11:11 +0000 on 04 Mar (1299237101), MaoXiaoyun wrote: > > > Hi: > > > > > > I''ve been testing on memory overcommit on Xen by using balloon driver. > > > On our stress test, it is possilbe that heap memory in xen is use up. Thus the serial > > > port will show log as below: > > > > > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > > (XEN) paging_log_dirty_range: 138 failed page allocs while logging dirty pages > > > > > > I am asking is it harmfull to domain? > > > > It means that the log-dirty code wasn''t able to extend its bitmap and > > callers have to assume that all pages are dirty. It''s bad for > > performance but should be OK. > > > > If you rebase to the latest 4.1 RC, this particular message should go > > away as log-dirty bitmaps are no longer pulled from common memory. > > > > > If so, I might need find a way to reserve some memory for xen, which looks > > > kinds of difficult. > > > > I think you might find you need to do this anyway - there are other > > dynamic allocations in Xen which might not fail so gracefully (in > > particular around setting up new domains). > > > > Tim. > > > > -- > > Tim Deegan <Tim.Deegan@citrix.com> > > Principal Software Engineer, Xen Platform Team > > Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)-- Tim Deegan <Tim.Deegan@citrix.com> Principal Software Engineer, Xen Platform Team Citrix Systems UK Ltd. (Company #02937203, SL9 0BG) _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Stefano Stabellini
2011-Mar-07 16:16 UTC
Re: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
On Mon, 7 Mar 2011, Tim Deegan wrote:> At 03:41 +0000 on 07 Mar (1299469316), MaoXiaoyun wrote: > > Thanks Tim. > > > > Do you have suggestion on how many memory I should reserved, is 512M > > enough? There is a balloon daemon process in dom0 do the memory > > management, the striaght way to reserve memory is after recycle memory > > form domains which no need memory , then give the memory to those > > domains who need memory. What do you think of this? > > Maybe the people who have been working on the toolstack can answer this > one - 512MiB free sounds like more than enough to me but I could be > wrong.give a look at how freememslack is set in tools/libxl/libxl.c:libxl__fill_dom0_memory_info: free_mem_slack_kb = (uint32_t) (PAGE_TO_MEMKB(physinfo.total_pages) - info.current_memkb); /* From empirical measurements the free_mem_slack shouldn''t be more * than 15% of the total memory present on the system. */ if (free_mem_slack_kb > PAGE_TO_MEMKB(physinfo.total_pages) * 0.15) free_mem_slack_kb = PAGE_TO_MEMKB(physinfo.total_pages) * 0.15; libxl__xs_write(gc, t, free_mem_slack_path, "%"PRIu32, free_mem_slack_kb); the memory left free in the system is never more than 15% of the total memory available and is calculated as the difference between physinfo.total_pages (total pages in the system) and info.current_memkb (memory currently used by dom0 at boot). _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
MaoXiaoyun
2011-Mar-08 01:53 UTC
RE: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
Thank stefano. It looks like free_mem_slack_kb refer to dom0, right? But, in my situation, since I use a balloond to management the memory resources between all domains(except dom0, for performance consideration), it is possible all memory is given to domU, which will cause some unexpect problems. So am ask is there a considerable memory amout need to be reserved for Xen itself. thanks.> Date: Mon, 7 Mar 2011 16:16:55 +0000 > From: stefano.stabellini@eu.citrix.com > To: Tim.Deegan@eu.citrix.com > CC: tinnycloud@hotmail.com; xen-devel@lists.xensource.com; Stefano.Stabellini@eu.citrix.com > Subject: Re: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull? > > On Mon, 7 Mar 2011, Tim Deegan wrote: > > At 03:41 +0000 on 07 Mar (1299469316), MaoXiaoyun wrote: > > > Thanks Tim. > > > > > > Do you have suggestion on how many memory I should reserved, is 512M > > > enough? There is a balloon daemon process in dom0 do the memory > > > management, the striaght way to reserve memory is after recycle memory > > > form domains which no need memory , then give the memory to those > > > domains who need memory. What do you think of this? > > > > Maybe the people who have been working on the toolstack can answer this > > one - 512MiB free sounds like more than enough to me but I could be > > wrong. > > give a look at how freememslack is set in > tools/libxl/libxl.c:libxl__fill_dom0_memory_info: > > free_mem_slack_kb = (uint32_t) (PAGE_TO_MEMKB(physinfo.total_pages) - > info.current_memkb); > /* From empirical measurements the free_mem_slack shouldn''t be more > * than 15% of the total memory present on the system. */ > if (free_mem_slack_kb > PAGE_TO_MEMKB(physinfo.total_pages) * 0.15) > free_mem_slack_kb = PAGE_TO_MEMKB(physinfo.total_pages) * 0.15; > libxl__xs_write(gc, t, free_mem_slack_path, "%"PRIu32, free_mem_slack_kb); > > the memory left free in the system is never more than 15% of the total > memory available and is calculated as the difference between > physinfo.total_pages (total pages in the system) and info.current_memkb > (memory currently used by dom0 at boot)._______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Stefano Stabellini
2011-Mar-08 11:14 UTC
RE: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?
On Tue, 8 Mar 2011, MaoXiaoyun wrote:> Thank stefano. > > It looks like free_mem_slack_kb refer to dom0, right? > > But, in my situation, since I use a balloond to management the memory resources > between all domains(except dom0, for performance consideration), it is possible > all memory is given to domU, which will cause some unexpect problems. > > So am ask is there a considerable memory amout need to be reserved for Xen itself. > thanks.free_mem_slack_kb is the amount of memory to be left free in the system for Xen. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel