From: Jeremy Fitzhardinge <jeremy@goop.org>
To: "Xu, Dongxiao" <dongxiao.xu@intel.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
Christophe Saout <christophe@saout.de>
Subject: Re: new netfront and occasional receive path lockup
Date: Fri, 10 Sep 2010 12:42:32 +1000 [thread overview]
Message-ID: <4C899B18.3040104@goop.org> (raw)
In-Reply-To: <D5AB6E638E5A3E4B8F4406B113A5A19A2A5ED798@shsmsx501.ccr.corp.intel.com>
On 09/10/2010 12:37 PM, Xu, Dongxiao wrote:
>> However, I am concerned about these manipulations of a cross-cpu
>> shared variable without any barriers or other ordering constraints.
>> Are you sure this code is correct under any reordering (either by the
>> compiler or CPUs); and if the compiler decides to access it more or
>> less often than the source says it should?
> Do you mean the flag "np->rx.sring->private.netif.smartpoll_active"?
> It is a flag in shared ring structure, Therefore operations towards
> this flag are the same as other component in shared ring, such as
> under spinlock, etc.
Spinlocks are no use for inter-domain synchronization, only within a
domain. The other ring operations are carefully ordered with
appropriate memory barriers in specific places; that's why I'm a bit
concerned about their absence for the smartpoll_active flag. Even if
they are not necessary, I'd like to see an analysis as to why.
J
next prev parent reply other threads:[~2010-09-10 2:42 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-22 16:43 new netfront and occasional receive path lockup Christophe Saout
2010-08-22 18:37 ` Christophe Saout
2010-08-24 0:53 ` Jeremy Fitzhardinge
2010-08-23 14:26 ` Christophe Saout
2010-08-23 16:04 ` Konrad Rzeszutek Wilk
2010-08-23 17:09 ` Christophe Saout
2010-08-24 0:46 ` Jeremy Fitzhardinge
2010-08-25 0:51 ` Xu, Dongxiao
2010-09-09 18:50 ` Pasi Kärkkäinen
2010-09-10 0:55 ` Jeremy Fitzhardinge
2010-09-10 1:45 ` Xu, Dongxiao
2010-09-10 2:25 ` Jeremy Fitzhardinge
2010-09-10 2:37 ` Xu, Dongxiao
2010-09-10 2:42 ` Jeremy Fitzhardinge [this message]
2010-09-12 1:00 ` Gerald Turner
2010-09-12 8:55 ` Jeremy Fitzhardinge
2010-09-12 17:23 ` Pasi Kärkkäinen
2010-09-12 22:40 ` Gerald Turner
2010-09-13 0:03 ` Gerald Turner
2010-09-13 0:54 ` Xu, Dongxiao
2010-09-13 2:12 ` Gerald Turner
2010-09-13 2:34 ` Xu, Dongxiao
2010-09-13 4:38 ` Gerald Turner
2010-09-13 16:01 ` Gerald Turner
2010-09-13 16:08 ` Pasi Kärkkäinen
2010-09-13 19:36 ` Jeremy Fitzhardinge
2010-09-14 8:25 ` Ian Campbell
2010-09-14 17:54 ` Jeremy Fitzhardinge
2010-09-14 18:44 ` Pasi Kärkkäinen
2010-09-15 9:46 ` Ian Campbell
2010-09-14 0:26 ` Xu, Dongxiao
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=4C899B18.3040104@goop.org \
--to=jeremy@goop.org \
--cc=christophe@saout.de \
--cc=dongxiao.xu@intel.com \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.