linux-kernel - Re: [RFC PATCH 1/3] sched/core: add API for exporting runqueue clock

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]

Date:   Thu, 19 Dec 2019 09:29:14 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>, Jens Axboe <axboe@...nel.dk>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Long Li <longli@...rosoft.com>, Ingo Molnar <mingo@...hat.com>,
        Keith Busch <keith.busch@...el.com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        John Garry <john.garry@...wei.com>,
        Hannes Reinecke <hare@...e.com>
Subject: Re: [RFC PATCH 1/3] sched/core: add API for exporting runqueue clock

On Wed, Dec 18, 2019 at 10:51:01AM +0100, Peter Zijlstra wrote:
> On Wed, Dec 18, 2019 at 03:19:40PM +0800, Ming Lei wrote:
> > Scheduler runqueue maintains its own software clock that is periodically
> > synchronised with hardware. Export this clock so that it can be used
> > by interrupt flood detection for saving the cost of reading from hardware.
> 
> But you don't have much, if any, guarantees the thing gets updated.

Any software clock won't be guaranteed to be updated in time, however,
they are still useful.

Thanks,
Ming