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From: Paolo Bonzini <bonzini@gnu.org>
To: Davide Libenzi <davidel@xmailserver.org>
Cc: Avi Kivity <avi@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	gleb@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: Tue, 25 Aug 2009 08:59:33 +0200	[thread overview]
Message-ID: <4A938BD5.1050302@gnu.org> (raw)
In-Reply-To: <alpine.DEB.2.00.0908241515150.7951@makko.or.mcafeemobile.com>


>>> There are userspace libraries that do almost everything, but you hardly
>>> see things like pthread_(EFD_STATE-like)_create() or similar system
>>> interfaces based on such abstraction.
>>
>> It actually seems as close to a condition variable as an eventfd can be.
>
> A pthread condition typical code usage maps to eventfd like:
>
> 	while (read(efd, ...)>  0)
> 		if (CONDITION)
> 			break;
>
> So a pthread condition is really a wakeup gate like eventfd is.
> EFD_STATE has nothing to do with a pthread condition.

No, your code does not work for pthread_cond_broadcast (which arguably 
is the common case) because all the eventfd readers after the first 
would block.

Paolo

  reply	other threads:[~2009-08-25  6:59 UTC|newest]

Thread overview: 47+ 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 [this message]
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
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

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