From: Guenter Roeck <linux@roeck-us.net>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Anton Blanchard <anton@ozlabs.org>
Subject: Re: [PATCH v1] fs/epoll: use a per-cpu counter for user's watches count
Date: Wed, 4 Aug 2021 08:22:22 -0700 [thread overview]
Message-ID: <20210804152222.GA3717568@roeck-us.net> (raw)
In-Reply-To: <20210802032013.2751916-1-npiggin@gmail.com>
On Mon, Aug 02, 2021 at 01:20:13PM +1000, Nicholas Piggin wrote:
> This counter tracks the number of watches a user has, to compare against
> the 'max_user_watches' limit. This causes a scalability bottleneck on
> SPECjbb2015 on large systems as there is only one user. Changing to a
> per-cpu counter increases throughput of the benchmark by about 30% on a
> 16-socket, > 1000 thread system.
>
> Reported-by: Anton Blanchard <anton@ozlabs.org>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
With all tinyconfig builds (and all other builds with CONFIG_EPOLL=n),
this patch results in:
kernel/user.c: In function 'free_user':
kernel/user.c:141:35: error: 'struct user_struct' has no member named 'epoll_watches'
141 | percpu_counter_destroy(&up->epoll_watches);
| ^~
kernel/user.c: In function 'alloc_uid':
kernel/user.c:189:45: error: 'struct user_struct' has no member named 'epoll_watches'
189 | if (percpu_counter_init(&new->epoll_watches, 0, GFP_KERNEL)) {
| ^~
kernel/user.c:203:52: error: 'struct user_struct' has no member named 'epoll_watches'
203 | percpu_counter_destroy(&new->epoll_watches);
| ^~
kernel/user.c: In function 'uid_cache_init':
kernel/user.c:225:43: error: 'struct user_struct' has no member named 'epoll_watches'
225 | if (percpu_counter_init(&root_user.epoll_watches, 0, GFP_KERNEL))
| ^
Guenter
next prev parent reply other threads:[~2021-08-04 15:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-02 3:20 [PATCH v1] fs/epoll: use a per-cpu counter for user's watches count Nicholas Piggin
2021-08-04 15:22 ` Guenter Roeck [this message]
2021-08-04 19:06 ` Randy Dunlap
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