linux-kernel - Re: Expense of read

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: <20210121154744.GQ2260413@casper.infradead.org>
Date:   Thu, 21 Jan 2021 15:47:44 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Mikulas Patocka <mpatocka@...hat.com>
Cc:     Jan Kara <jack@...e.cz>, Dave Chinner <david@...morbit.com>,
        Zhongwei Cai <sunrise_l@...u.edu.cn>,
        Theodore Ts'o <tytso@....edu>,
        David Laight <David.Laight@...lab.com>,
        Mingkai Dong <mingkaidong@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Whitehouse <swhiteho@...hat.com>,
        Eric Sandeen <esandeen@...hat.com>,
        Dave Chinner <dchinner@...hat.com>,
        Wang Jianchao <jianchao.wan9@...il.com>,
        Rajesh Tadakamadla <rajesh.tadakamadla@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>
Subject: Re: Expense of read_iter

On Wed, Jan 20, 2021 at 10:12:01AM -0500, Mikulas Patocka wrote:
> Do you have some idea how to optimize the generic code that calls 
> ->read_iter?

Yes.

> It might be better to maintain an f_iocb_flags in the
> struct file and just copy that unconditionally.  We'd need to remember
> to update it in fcntl(F_SETFL), but I think that's the only place.

Want to give that a try?