From: David Vrabel <david.vrabel@citrix.com>
To: Tim Deegan <tim@xen.org>
Cc: Wei Liu <wei.liu2@citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
"Keir (Xen.org)" <keir@xen.org>, Jan Beulich <JBeulich@suse.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 8/8] evtchn: add FIFO-based event channel hypercalls and port ops
Date: Wed, 20 Mar 2013 14:38:20 +0000 [thread overview]
Message-ID: <5149C9DC.3050806@citrix.com> (raw)
In-Reply-To: <20130320142358.GA95617@ocelot.phlegethon.org>
On 20/03/13 14:23, Tim Deegan wrote:
> At 13:55 +0000 on 20 Mar (1363787704), Jan Beulich wrote:
>>>>> On 20.03.13 at 14:42, David Vrabel <david.vrabel@citrix.com> wrote:
>>> On 20/03/13 10:47, Jan Beulich wrote:
>>>>>>> On 19.03.13 at 22:00, David Vrabel <david.vrabel@citrix.com> wrote:
>>>>> +struct evtchn_fifo_queue {
>>>>> + volatile uint32_t *head; /* points into control block */
>>>>
>>>> I still think that explicit barriers are the way to go. Unless Linux'es
>>>> view on this has changed, you'll have issues getting the Linux folks
>>>> to accept this.
>>>
>>> This volatile can just be removed. head is only written by Xen in one
>>> place and it is immediately followed by a spin_unlock() which is a barrier.
>>
>> A release type barrier only, but that presumably is sufficient for
>> the purposes here.
>
> You might have to use an atomic_t or similar if the consumer might be
> confused by partial updates.
I have assumed that reads and writes to 32-bit words are atomic on all
interesting architectures.
David
next prev parent reply other threads:[~2013-03-20 14:38 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-19 21:00 [PATCH RFC 0/8] Xen: FIFO-based event channel ABI David Vrabel
2013-03-19 21:00 ` [PATCH 1/8] debug: remove some event channel info from the 'i' and 'q' debug keys David Vrabel
2013-03-19 21:00 ` [PATCH 2/8] evtchn: refactor low-level event channel port ops David Vrabel
2013-03-20 10:21 ` Jan Beulich
2013-03-20 13:37 ` David Vrabel
2013-03-20 10:24 ` Jan Beulich
2013-03-19 21:00 ` [PATCH 3/8] evtchn: add a hook to bind an event port to a VCPU David Vrabel
2013-03-19 21:00 ` [PATCH 4/8] evtchn: Dynamically allocate d->evtchn David Vrabel
2013-03-20 11:43 ` Wei Liu
2013-03-19 21:00 ` [PATCH 5/8] evtchn: use a per-domain variable for the max number of event channels David Vrabel
2013-03-20 10:27 ` Jan Beulich
2013-03-19 21:00 ` [PATCH 6/8] HACK! evtchn: increase number of buckets to support the FIFO ABI David Vrabel
2013-03-19 21:00 ` [PATCH 7/8] evtchn: add FIFO-based event channel ABI David Vrabel
2013-03-20 10:32 ` Jan Beulich
2013-03-20 13:38 ` David Vrabel
2013-03-19 21:00 ` [PATCH 8/8] evtchn: add FIFO-based event channel hypercalls and port ops David Vrabel
2013-03-20 10:47 ` Jan Beulich
2013-03-20 13:42 ` David Vrabel
2013-03-20 13:55 ` Jan Beulich
2013-03-20 14:23 ` Tim Deegan
2013-03-20 14:38 ` David Vrabel [this message]
2013-03-20 15:34 ` Tim Deegan
2013-03-20 15:54 ` David Vrabel
2013-03-20 16:15 ` Keir Fraser
2013-03-20 13:50 ` Wei Liu
2013-03-19 21:15 ` [PATCH RFC 0/8] Xen: FIFO-based event channel ABI Keir Fraser
2013-03-20 10:15 ` Jan Beulich
-- strict thread matches above, loose matches on Subject: below --
2013-08-09 18:08 [RFC PATCH " David Vrabel
2013-08-09 18:08 ` [PATCH 8/8] evtchn: add FIFO-based event channel hypercalls and port ops David Vrabel
2013-08-16 16:33 ` Wei Liu
2013-08-19 10:32 ` David Vrabel
2013-08-19 10:46 ` Wei Liu
2013-08-23 10:33 ` Jan Beulich
2013-08-23 11:00 ` David Vrabel
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=5149C9DC.3050806@citrix.com \
--to=david.vrabel@citrix.com \
--cc=JBeulich@suse.com \
--cc=keir@xen.org \
--cc=konrad.wilk@oracle.com \
--cc=tim@xen.org \
--cc=wei.liu2@citrix.com \
--cc=xen-devel@lists.xen.org \
/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).