linux-kernel - Re: O_NONBLOCK is NOOP on block devices

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <x494oko5n2o.fsf@segfault.boston.devel.redhat.com>
Date:	Wed, 10 Mar 2010 08:21:51 -0500
From:	Jeff Moyer <jmoyer@...hat.com>
To:	M vd S <mvds.00@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: O_NONBLOCK is NOOP on block devices

M vd S <mvds.00@...il.com> writes:
> I also briefly tried aio_* and the libaio interface. The former is not
> really asynchronous - all requests are put in one separate thread
> where they will be executed in order, i.e. blocking, so you don't get
> any advantage from NCQ or data that was cached by the disk or the
> kernel. The latter apparently ends in an io_submit() which will block
> until all queued reads are finished, but I might have missed something
> there.

What you missed is that the native aio system calls require O_DIRECT.

Cheers,
Jeff
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/