From: Andrew Morton <akpm@linux-foundation.org>
To: Jim Newsome <jnewsome@torproject.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Christian Brauner <christian@brauner.io>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5] do_wait: make PIDTYPE_PID case O(1) instead of O(n)
Date: Fri, 12 Mar 2021 10:22:07 -0800 [thread overview]
Message-ID: <20210312102207.a347e38db375226a78cc37bf@linux-foundation.org> (raw)
In-Reply-To: <20210312173855.24843-1-jnewsome@torproject.org>
On Fri, 12 Mar 2021 11:38:55 -0600 Jim Newsome <jnewsome@torproject.org> 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.
Could we please see some performance testing results to permit us to
evaluate the value of this change?
Thanks.
next prev parent reply other threads:[~2021-03-12 18:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 17:38 [PATCH v5] do_wait: make PIDTYPE_PID case O(1) instead of O(n) Jim Newsome
2021-03-12 18:22 ` Andrew Morton [this message]
2021-03-12 18:39 ` Jim Newsome
2021-03-12 18:47 ` Andrew Morton
2021-03-13 2:42 ` Jim Newsome
2021-03-12 20:01 ` Jim Newsome
2021-03-12 20:29 ` Eric W. Biederman
2021-03-12 21:05 ` Jim Newsome
2021-03-12 21:25 ` Eric W. Biederman
2021-03-13 17:25 ` Oleg Nesterov
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