RE: [Xen-devel] is paging_new_log_dirty_page alloc page harmfull?

[MaoXiaoyun <tinnycloud@xxxxxxxxxxx>]

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@xxxxxxxxxx
> To: tinnycloud@xxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxxxxxxxx
> 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 ex tend 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@xxxxxxxxxx>
> Principal Software Engineer, Xen Platform Team
> Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)

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