From: Oleg Nesterov <oleg@redhat.com>
To: Jim Newsome <jnewsome@torproject.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Christian Brauner <christian@brauner.io>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] do_wait: make PIDTYPE_PID case O(1) instead of O(n)
Date: Wed, 10 Mar 2021 18:27:53 +0100 [thread overview]
Message-ID: <20210310172752.GA8973@redhat.com> (raw)
In-Reply-To: <20210309203919.15920-1-jnewsome@torproject.org>
On 03/09, Jim Newsome wrote:
>
> do_wait is an internal function used to implement waitpid, waitid,
> wait4, etc. To handle the general case, it does an O(n) linear scan of
> the thread group's children and tracees.
>
> This patch adds a special-case when waiting on a pid to skip these scans
> and instead do an O(1) lookup. This improves performance when waiting on
> a pid from a thread group with many children and/or tracees.
>
> Signed-off-by: James Newsome <jnewsome@torproject.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
next prev parent reply other threads:[~2021-03-10 17:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 20:39 [PATCH v3] do_wait: make PIDTYPE_PID case O(1) instead of O(n) Jim Newsome
2021-03-10 17:27 ` Oleg Nesterov [this message]
2021-03-10 22:40 ` Eric W. Biederman
2021-03-11 0:14 ` Jim Newsome
2021-03-11 15:15 ` Oleg Nesterov
2021-03-11 16:26 ` Jim Newsome
2021-03-11 16:30 ` Eric W. Biederman
2021-03-11 15:08 ` Oleg Nesterov
2021-03-11 16:37 ` Eric W. Biederman
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