linux-kernel - Re: [PATCH-tip v2 06/12] locking/rwsem: Wake up almost all readers in wait queue

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190410172254.ivgcgehjhqgwjtda@linux-r8p5>
Date:   Wed, 10 Apr 2019 10:22:54 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Waiman Long <longman@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>
Subject: Re: [PATCH-tip v2 06/12] locking/rwsem: Wake up almost all readers
 in wait queue

On Wed, 10 Apr 2019, Waiman Long wrote:
>There are 2 major reasons why there is a limit.
>
>1) It will be unfair to the task that needs to spend so much of its own
>CPU time to wake up too many readers.

This has never been a problem before.

>2) I want to avoid the extreme case that there are more than 32k readers
>in the wait queue and make the count overflow.

But in this case the readers are already on the queue.

Thanks,
Davidlohr