lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 7 Jul 2014 21:06:37 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Jason Low <jason.low2@...com>
Cc: torvalds@...ux-foundation.org, paulmck@...ux.vnet.ibm.com,
mingo@...nel.org, Waiman.Long@...com, davidlohr@...com,
linux-kernel@...r.kernel.org, tglx@...utronix.de, riel@...hat.com,
rostedt@...dmis.org, akpm@...ux-foundation.org, hpa@...or.com,
tim.c.chen@...ux.intel.com, konrad.wilk@...cle.com, aswin@...com,
scott.norton@...com, chegu_vinod@...com, david@...morbit.com
Subject: Re: [PATCH 0/4] MCS spinlocks: Cancellable MCS spinlock rework
On Mon, Jul 07, 2014 at 11:50:15AM -0700, Jason Low wrote:
> The main purpose of this patchset is to reduce the size of the
> cancellable MCS spinlock and reduce the overhead of rwsem
> (currently the largest lock in the kernel).
>
> The overhead of the cancellable MCS lock is a pointer to a per-cpu node
> structure which requires 64 bits on 64 bit systems. Instead of a pointer
> to the per-cpu node, we can instead store the CPU # corresponding to the
> node in atomic_t. This reduces the overhead by 32 bits on 64 bit systems.
>
> This then opens the opportunity to reduce the size of the rw_semaphore
> structure (one of the current users of this MCS lock) by moving around some
> of its fields. Due to padding, we would reduce the size of that structure
> by 64 bits (on 64 bit systems). This makes it more in line with the size
> of the mutex structure.
Dave Chinner was very interested in this..
Content of type "application/pgp-signature" skipped
Powered by blists - more mailing lists