linux-kernel - Re: NFS: 82ms wakeup latency 4.14-rc4

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: <1513618019.7113.27.camel@gmx.de>
Date:   Mon, 18 Dec 2017 18:26:59 +0100
From:   Mike Galbraith <efault@....de>
To:     Trond Myklebust <trondmy@...marydata.com>,
        "bfields@...ldses.org" <bfields@...ldses.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "jlayton@...nel.org" <jlayton@...nel.org>
Subject: Re: NFS: 82ms wakeup latency 4.14-rc4

On Mon, 2017-12-18 at 17:24 +0000, Trond Myklebust wrote:
> On Mon, 2017-12-18 at 18:00 +0100, Mike Galbraith wrote:
> > On Mon, 2017-12-18 at 11:35 -0500, J. Bruce Fields wrote:
> > > 
> > > Like I say, I don't really understand the issues here, so it's more
> > > a
> > > question than an objection....  (I don't know any reason a
> > > cond_resched() would be bad there.)
> > 
> > Think of it this way: what all can be queued up behind that kworker
> > that is hogging CPU for huge swaths of time?  It's not only userspace
> > that suffers.
> > 
> 
> Any cond_sched() belongs in the loop in nfs_commit_release_pages()
> (where it can be mitigated) rather than in a function whose purpose is
> to free memory. There is no reason to call it from the writeback or
> readpages code.

(this is why bandaid didn't come equipped with changelog etc:)