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
| ||
|
Message-ID: <CAJfpegvv-SPJRjWrR_+JY-H=xmYq0pnTfAtj-N8kG7AnQvWd=w@mail.gmail.com> Date: Tue, 18 Apr 2023 14:42:03 +0200 From: Miklos Szeredi <miklos@...redi.hu> To: Jens Axboe <axboe@...nel.dk> Cc: "Darrick J. Wong" <djwong@...nel.org>, Christoph Hellwig <hch@...radead.org>, Bernd Schubert <bschubert@....com>, io-uring@...r.kernel.org, linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org, dsingh@....com Subject: Re: [PATCH 1/2] fs: add FMODE_DIO_PARALLEL_WRITE flag On Sat, 15 Apr 2023 at 15:15, Jens Axboe <axboe@...nel.dk> wrote: > Yep, that is pretty much it. If all writes to that inode are serialized > by a lock on the fs side, then we'll get a lot of contention on that > mutex. And since, originally, nothing supported async writes, everything > would get punted to the io-wq workers. io_uring added per-inode hashing > for this, so that any punt to io-wq of a write would get serialized. > > IOW, it's an efficiency thing, not a correctness thing. We could still get a performance regression if the majority of writes still trigger the exclusive locking. The questions are: - how often does that happen in real life? - how bad the performance regression would be? Without first attempting to answer those questions, I'd be reluctant to add FMODE_DIO_PARALLEL_WRITE to fuse. Thanks, Miklos
Powered by blists - more mailing lists