linux-kernel - Re: [PATCH 5/5] aio: Refactor aio_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] [day] [month] [year] [list]

Date:	Thu, 11 Oct 2012 09:43:12 -0700
From:	Zach Brown <zab@...hat.com>
To:	Kent Overstreet <koverstreet@...gle.com>
Cc:	linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
	dm-devel@...hat.com, tytso@....edu
Subject: Re: [PATCH 5/5] aio: Refactor aio_read_evt, use cmxchg(), fix bug

> Yeah, but that means the completion has to be delivered from process
> context. That's not what aio does today, and it'd be a real performance
> regression.

It'd only have to to complete from process context if it faults. The
cheapest possible delivery mechanism is simple cpu stores.  In the vast
majority of cases the ring will be resident and it'll be done.  In rare
cases it could fall back to a deferred completion.  If apps can't
stomach that latency and want to pay the overhead of pinning to remove
that risk, they're welcome to do so.

That's my hope, anyway.

- z
--
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/