From: Zebediah Figura <z.figura12@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>,
Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: tglx@linutronix.de, mingo@redhat.com, dvhart@infradead.org,
linux-kernel@vger.kernel.org, kernel@collabora.com,
Steven Noonan <steven@valvesoftware.com>,
"Pierre-Loup A . Griffais" <pgriffais@valvesoftware.com>,
viro@zeniv.linux.org.uk, jannh@google.com
Subject: Re: [PATCH RFC 2/2] futex: Implement mechanism to wait on any of several futexes
Date: Wed, 31 Jul 2019 10:15:49 -0500 [thread overview]
Message-ID: <306b3332-0065-59dc-e6d6-ee3c8a67ef53@gmail.com> (raw)
In-Reply-To: <20190731120600.GT31381@hirez.programming.kicks-ass.net>
On 7/31/19 7:06 AM, Peter Zijlstra wrote:
> On Tue, Jul 30, 2019 at 06:06:02PM -0400, Gabriel Krisman Bertazi wrote:
>> This is a new futex operation, called FUTEX_WAIT_MULTIPLE, which allows
>> a thread to wait on several futexes at the same time, and be awoken by
>> any of them. In a sense, it implements one of the features that was
>> supported by pooling on the old FUTEX_FD interface.
>>
>> My use case for this operation lies in Wine, where we want to implement
>> a similar interface available in Windows, used mainly for event
>> handling. The wine folks have an implementation that uses eventfd, but
>> it suffers from FD exhaustion (I was told they have application that go
>> to the order of multi-milion FDs), and higher CPU utilization.
>
> So is multi-million the range we expect for @count ?
>
Not in Wine's case; in fact Wine has a hard limit of 64 synchronization
primitives that can be waited on at once (which, with the current
user-side code, translates into 65 futexes). The exhaustion just had to
do with the number of primitives created; some programs seem to leak
them badly.
next prev parent reply other threads:[~2019-07-31 15:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 22:06 [PATCH RFC 1/2] futex: Split key setup from key queue locking and read Gabriel Krisman Bertazi
2019-07-30 22:06 ` [PATCH RFC 2/2] futex: Implement mechanism to wait on any of several futexes Gabriel Krisman Bertazi
2019-07-31 12:06 ` Peter Zijlstra
2019-07-31 15:15 ` Zebediah Figura [this message]
2019-07-31 22:39 ` Thomas Gleixner
2019-07-31 23:02 ` Zebediah Figura
2019-08-06 6:26 ` Gabriel Krisman Bertazi
2019-08-06 10:13 ` Peter Zijlstra
2019-08-01 0:45 ` Thomas Gleixner
2019-08-01 1:22 ` Zebediah Figura
2019-08-01 1:32 ` Zebediah Figura
2019-08-01 1:42 ` Pierre-Loup A. Griffais
2019-07-31 23:33 ` [PATCH RFC 1/2] futex: Split key setup from key queue locking and read Thomas Gleixner
2019-08-01 0:07 ` Gabriel Krisman Bertazi
2019-08-01 0:22 ` Gabriel Krisman Bertazi
2019-08-01 0:41 ` Thomas Gleixner
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