From: Gleb Natapov <gleb@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Davide Libenzi <davidel@xmailserver.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
kvm@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/2] eventfd: new EFD_STATE flag
Date: Wed, 26 Aug 2009 22:50:02 +0300 [thread overview]
Message-ID: <20090826195002.GE11762@redhat.com> (raw)
In-Reply-To: <4A95900D.9090201@redhat.com>
On Wed, Aug 26, 2009 at 10:42:05PM +0300, Avi Kivity wrote:
> On 08/26/2009 10:13 PM, Davide Libenzi wrote:
> >Ok, so why not using the eventfd counter as state?
> >On the device side:
> >
> >void write_state(int sfd, int state) {
> > u64 cnt;
> >
> > /* Clear the current state, sfd is in non-blocking mode */
> > read(sfd,&cnt, sizeof(cnt));
> > /* Writes new state */
> > cnt = 1 + !!state;
> > write(sfd,&cnt, sizeof(cnt));
> >}
> >
> >
> >On the hypervisor side:
> >
> >int read_state(int sfd) {
> > u64 cnt;
> >
> > read(sfd,&cnt, sizeof(cnt));
> > return state - 1;
> >}
> >
>
> Hadn't though of read+write as set. While the 1+ is a little ugly,
> it's workable.
>
It's two system calls instead of one to inject interrupt.
> I see no kernel equivalent to read(), but that's easily done.
>
--
Gleb.
next prev parent reply other threads:[~2009-08-26 19:50 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-20 15:56 [PATCH 0/2] eventfd: new EFD_STATE flag Michael S. Tsirkin
2009-08-20 16:20 ` Davide Libenzi
2009-08-20 17:38 ` Avi Kivity
2009-08-20 17:44 ` Davide Libenzi
2009-08-20 17:56 ` Paolo Bonzini
2009-08-21 17:21 ` Davide Libenzi
2009-08-20 17:55 ` Michael S. Tsirkin
2009-08-20 18:06 ` Avi Kivity
2009-08-20 18:28 ` Michael S. Tsirkin
2009-08-23 13:01 ` Avi Kivity
2009-08-23 13:36 ` Michael S. Tsirkin
2009-08-23 13:40 ` Avi Kivity
2009-08-23 14:30 ` Michael S. Tsirkin
2009-08-23 16:51 ` Paolo Bonzini
2009-08-24 18:25 ` Davide Libenzi
2009-08-24 18:31 ` Avi Kivity
2009-08-24 22:08 ` Davide Libenzi
2009-08-24 22:10 ` Paolo Bonzini
2009-08-24 22:32 ` Davide Libenzi
2009-08-25 6:59 ` Paolo Bonzini
2009-08-25 4:26 ` Avi Kivity
2009-08-24 21:49 ` Michael S. Tsirkin
2009-08-24 22:15 ` Davide Libenzi
2009-08-25 7:22 ` Michael S. Tsirkin
2009-08-25 21:57 ` Davide Libenzi
2009-08-26 10:29 ` Michael S. Tsirkin
2009-08-26 10:41 ` Avi Kivity
2009-08-26 17:45 ` Davide Libenzi
2009-08-26 18:58 ` Avi Kivity
2009-08-26 19:13 ` Davide Libenzi
2009-08-26 19:42 ` Avi Kivity
2009-08-26 19:44 ` Davide Libenzi
2009-08-26 23:30 ` Davide Libenzi
2009-08-27 4:13 ` Avi Kivity
2009-08-27 8:06 ` Michael S. Tsirkin
2009-08-27 14:20 ` Davide Libenzi
2009-08-26 19:50 ` Gleb Natapov [this message]
2009-08-26 20:04 ` Davide Libenzi
2009-08-27 5:25 ` Gleb Natapov
2009-08-27 9:05 ` Paolo Bonzini
2009-08-27 9:09 ` Michael S. Tsirkin
2009-08-27 14:21 ` Davide Libenzi
2009-08-27 14:30 ` Michael S. Tsirkin
2009-08-27 14:38 ` Davide Libenzi
2009-08-27 14:49 ` Michael S. Tsirkin
2009-08-27 15:29 ` Davide Libenzi
2009-08-27 17:09 ` Davide Libenzi
[not found] ` <alpine.DEB.2.00.0908311644410.17349@makko.or.mcafeemobile.com>
[not found] ` <4A9CB318.7030401@redhat.com>
[not found] ` <alpine.DEB.2.00.0909010723380.28172@makko.or.mcafeemobile.com>
2010-01-06 19:33 ` Michael S. Tsirkin
2010-01-06 20:43 ` Davide Libenzi
2010-01-06 20:55 ` Michael S. Tsirkin
2010-01-06 21:17 ` Davide Libenzi
2010-01-06 22:29 ` Michael S. Tsirkin
2010-01-06 22:46 ` Davide Libenzi
2010-01-06 23:45 ` Michael S. Tsirkin
2010-01-06 23:59 ` Davide Libenzi
2010-01-07 0:02 ` Michael S. Tsirkin
2010-01-07 6:45 ` Michael S. Tsirkin
2010-01-07 7:25 ` Davide Libenzi
2010-01-07 10:36 ` Michael S. Tsirkin
2010-01-07 23:37 ` Davide Libenzi
2010-01-08 0:13 ` Davide Libenzi
2010-01-08 0:26 ` Davide Libenzi
2010-01-10 10:30 ` Michael S. Tsirkin
2010-01-10 15:26 ` Davide Libenzi
2010-01-10 16:22 ` Michael S. Tsirkin
2010-01-10 17:27 ` Davide Libenzi
2010-01-10 17:35 ` Michael S. Tsirkin
2010-01-10 19:04 ` Davide Libenzi
2010-01-11 7:34 ` Michael S. Tsirkin
2010-01-11 19:14 ` Davide Libenzi
2010-01-11 19:19 ` Michael S. Tsirkin
2010-01-11 22:53 ` Davide Libenzi
2010-01-13 17:07 ` Michael S. Tsirkin
2010-01-11 9:01 ` Gleb Natapov
2010-01-11 9:02 ` Michael S. Tsirkin
2010-01-11 9:08 ` Gleb Natapov
2010-01-11 9:19 ` Michael S. Tsirkin
2010-01-11 9:36 ` Gleb Natapov
2010-01-11 9:41 ` Michael S. Tsirkin
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