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  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:   Mon, 3 Feb 2020 18:44:21 +0100
From:   Christoph Hellwig <>
To:     Jan Kara <>
Cc:     Christoph Hellwig <>,,, Waiman Long <>,
        Peter Zijlstra <>,
        Thomas Gleixner <>,
        Ingo Molnar <>, Will Deacon <>,
        Andrew Morton <>,,,,
Subject: Re: RFC: hold i_rwsem until aio completes

On Thu, Jan 16, 2020 at 03:00:04PM +0100, Jan Kara wrote:
> I'd like to note that using i_dio_count has also one advantage you didn't
> mention. For AIO case, if you need to hold i_rwsem in exclusive mode,
> holding the i_rwsem just for submission part is a significant performance
> advantage (shorter lock hold times allow for higher IO parallelism). I
> guess this could be mitigated by downgrading the lock to shared mode
> once the IO is submitted. But there will be still some degradation visible
> for the cases of mixed exclusive and shared acquisitions because shared
> holders will be blocking exclusive ones for longer time.
> This may be especially painful for filesystems that don't implement DIO
> overwrites with i_rwsem in shared mode...

True.  Fortunately there are patches for ext4 out to move over to that
scheme.  gfs2 will need a little more attention, but that also for other

Powered by blists - more mailing lists