From: Keir Fraser <keir.xen@gmail.com>
To: "Liu.yi" <liu.yi24@zte.com.cn>, xen-devel@lists.xensource.com
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Subject: Re: credit scheduler svc->flags access race?
Date: Tue, 03 Jan 2012 07:33:28 +0000 [thread overview]
Message-ID: <CB285FC8.280CB%keir.xen@gmail.com> (raw)
In-Reply-To: <1325300125668-5111504.post@n5.nabble.com>
On 31/12/2011 02:55, "Liu.yi" <liu.yi24@zte.com.cn> wrote:
> hi,all
> In my HP DL380G7 server, csched_vcpu_yield and csched_acct may access
> svc->flags at the same time, when this happens vms stop running because
> csched_vcpu_yield overwrites svc->flags which csched_acct set to
> CSCHED_FLAG_VCPU_PARKED (My vm's schedule cap values is not 0).
> Vms run fine if I modified schedule_credit.c as follows:
Cc'ing George Dunlap. This is probably a good bug fix.
-- Keir
> --- xen/common/sched_credit.c 2010-12-10 10:19:45.000000000 +0800
> +++ ../../xen-4.1.0/xen/common/sched_credit.c 2010-12-31
> 10:47:39.000000000 +0800
> @@ -135,7 +135,7 @@ struct csched_vcpu {
> struct vcpu *vcpu;
> atomic_t credit;
> s_time_t start_time; /* When we were scheduled (used for credit) */
> - uint16_t flags;
> + uint32_t flags;
> int16_t pri;
> #ifdef CSCHED_STATS
> struct {
> @@ -787,7 +787,7 @@ csched_vcpu_yield(const struct scheduler
> if ( !sched_credit_default_yield )
> {
> /* Let the scheduler know that this vcpu is trying to yield */
> - sv->flags |= CSCHED_FLAG_VCPU_YIELD;
> + set_bit(1, &sv->flags);
> }
> }
>
> @@ -1086,7 +1086,7 @@ csched_acct(void* dummy)
> {
> CSCHED_STAT_CRANK(vcpu_park);
> vcpu_pause_nosync(svc->vcpu);
> - svc->flags |= CSCHED_FLAG_VCPU_PARKED;
> + set_bit(0, &svc->flags);
> }
>
> /* Lower bound on credits */
> @@ -1111,7 +1111,7 @@ csched_acct(void* dummy)
> */
> CSCHED_STAT_CRANK(vcpu_unpark);
> vcpu_unpause(svc->vcpu);
> - svc->flags &= ~CSCHED_FLAG_VCPU_PARKED;
> + clear_bit(0, &svc->flags);
> }
>
> /* Upper bound on credits means VCPU stops earning */
> @@ -1337,7 +1337,7 @@ csched_schedule(
> * Clear YIELD flag before scheduling out
> */
> if ( scurr->flags & CSCHED_FLAG_VCPU_YIELD )
> - scurr->flags &= ~(CSCHED_FLAG_VCPU_YIELD);
> + clear_bit(1, &scurr->flags);
>
> Are these modification correct? Another interesting thing is that vms run
> fine on other server even if these vms's credit cap value is not 0. I don't
> know why.
> My xen version is 4.1.0, dom0 kernel version is 2.6.32.41 from jerry's git a
> few months before.
>
> Thanks
>
> liuyi
>
>
> --
> View this message in context:
> http://xen.1045712.n5.nabble.com/credit-scheduler-svc-flags-access-race-tp5111
> 504p5111504.html
> Sent from the Xen - Dev mailing list archive at Nabble.com.
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
next prev parent reply other threads:[~2012-01-03 7:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-31 2:55 credit scheduler svc->flags access race? Liu.yi
2012-01-03 7:33 ` Keir Fraser [this message]
2012-01-04 23:02 ` George Dunlap
2012-01-05 2:36 ` Liu.yi
2012-01-05 7:58 ` Jan Beulich
2012-01-05 8:43 ` Liu.yi
-- strict thread matches above, loose matches on Subject: below --
2011-12-29 7:50 Liu,Yi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CB285FC8.280CB%keir.xen@gmail.com \
--to=keir.xen@gmail.com \
--cc=George.Dunlap@eu.citrix.com \
--cc=liu.yi24@zte.com.cn \
--cc=xen-devel@lists.xensource.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).