From: Anthony Liguori <anthony@codemonkey.ws>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Arun R Bharadwaj <arun@linux.vnet.ibm.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 2/3] Make paio subsystem use threadlets
Date: Wed, 20 Oct 2010 08:16:50 -0500 [thread overview]
Message-ID: <4CBEEBC2.1010007@codemonkey.ws> (raw)
In-Reply-To: <AANLkTimPnt=iUZNkKjnRqh1XJd1xMSf2Mv28s5t6790N@mail.gmail.com>
On 10/20/2010 04:30 AM, Stefan Hajnoczi wrote:
>
>> } else if (acb->ret == -EINPROGRESS) {
>> active = 1;
>> }
>> - mutex_unlock(&lock);
>>
>> if (active) {
>> /* fail safe: if the aio could not be canceled, we wait for
>>
> while (qemu_paio_error(acb) == EINPROGRESS)
> ;
>
> Tight loop with no memory barrier reading a memory location that is
> updated by another thread. We shouldn't communicate between threads
> without barriers.
>
We shouldn't use a tight loop period. A condition should be used if
signalling is needed.
And we shouldn't rely on atomic assignments to communicate between
threads. Just use a mutex and avoid being fancier than we need to be.
Regards,
Anthony Liguori
> Stefan
>
>
next prev parent reply other threads:[~2010-10-20 13:17 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-19 17:42 [Qemu-devel] v6: [PATCH 0/3]: Threadlets: A generic task offloading framework Arun R Bharadwaj
2010-10-19 17:42 ` [Qemu-devel] [PATCH 1/3] Introduce threadlets Arun R Bharadwaj
2010-10-19 18:36 ` Balbir Singh
2010-10-19 19:01 ` [Qemu-devel] " Paolo Bonzini
2010-10-19 19:12 ` Balbir Singh
2010-10-19 19:29 ` Paolo Bonzini
2010-10-19 21:00 ` [Qemu-devel] " Venkateswararao Jujjuri (JV)
2010-10-20 2:26 ` Balbir Singh
2010-10-19 21:36 ` Anthony Liguori
2010-10-20 2:22 ` Balbir Singh
2010-10-20 3:46 ` Venkateswararao Jujjuri (JV)
2010-10-20 13:05 ` Balbir Singh
2010-10-20 13:13 ` Anthony Liguori
2010-10-20 3:19 ` Venkateswararao Jujjuri (JV)
2010-10-20 8:16 ` Stefan Hajnoczi
2010-10-19 17:43 ` [Qemu-devel] [PATCH 2/3] Make paio subsystem use threadlets Arun R Bharadwaj
2010-10-20 2:24 ` Balbir Singh
2010-10-20 8:42 ` Kevin Wolf
2010-10-20 9:30 ` Stefan Hajnoczi
2010-10-20 13:16 ` Anthony Liguori [this message]
2010-10-21 8:40 ` Arun R Bharadwaj
2010-10-21 9:17 ` Stefan Hajnoczi
2010-10-19 17:43 ` [Qemu-devel] [PATCH 3/3] Add helper functions for virtio-9p to " Arun R Bharadwaj
2010-10-20 11:19 ` Stefan Hajnoczi
2010-10-20 13:17 ` Anthony Liguori
2010-10-20 11:57 ` [Qemu-devel] v6: [PATCH 0/3]: Threadlets: A generic task offloading framework Amit Shah
2010-10-20 12:05 ` Stefan Hajnoczi
2010-10-20 13:18 ` Anthony Liguori
2010-10-22 9:59 ` Amit Shah
2010-10-23 12:05 ` Stefan Hajnoczi
2010-10-27 7:57 ` Amit Shah
2010-10-27 8:37 ` Stefan Hajnoczi
-- strict thread matches above, loose matches on Subject: below --
2010-10-26 14:14 [Qemu-devel] v8: [PATCH 0/3] " Arun R Bharadwaj
2010-10-26 14:14 ` [Qemu-devel] [PATCH 2/3] Make paio subsystem use threadlets Arun R Bharadwaj
2010-10-27 9:17 ` Stefan Hajnoczi
2010-10-21 12:10 [Qemu-devel] [PATCH 0/3]: v7: Threadlets: A generic task offloading framework Arun R Bharadwaj
2010-10-21 12:10 ` [Qemu-devel] [PATCH 2/3] Make paio subsystem use threadlets Arun R Bharadwaj
2010-10-23 11:57 ` Stefan Hajnoczi
2010-10-13 16:44 [Qemu-devel] [PATCH 0/3]: Threadlets: A generic task offloading framework Arun R Bharadwaj
2010-10-13 16:48 ` [Qemu-devel] [PATCH 2/3]: Make paio subsystem use threadlets Arun R Bharadwaj
2010-10-13 15:30 [Qemu-devel] v5 [PATCH 0/3] qemu: Threadlets: A generic task offloading framework Arun R Bharadwaj
2010-10-13 15:31 ` [Qemu-devel] [PATCH 2/3] Make paio subsystem use threadlets Arun R Bharadwaj
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=4CBEEBC2.1010007@codemonkey.ws \
--to=anthony@codemonkey.ws \
--cc=arun@linux.vnet.ibm.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@gmail.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.