From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH 4/5] aio: vmap ringbuffer Date: Tue, 9 Oct 2012 18:09:03 -0700 Message-ID: <20121010010903.GC24174@moria.home.lan> References: <1349764760-21093-1-git-send-email-koverstreet@google.com> <1349764760-21093-4-git-send-email-koverstreet@google.com> <20121009182949.GO26187@lenny.home.zabbo.net> <20121009213111.GE29494@google.com> <20121009223210.GR26187@lenny.home.zabbo.net> <20121009224428.GH29494@google.com> <20121009225836.GU26187@lenny.home.zabbo.net> <20121010001630.GC26835@google.com> <20121010003626.GY26187@lenny.home.zabbo.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20121010003626.GY26187-fypN+1c5dIyjpB87vu3CluTW4wlIGRCZ@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Zach Brown Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, tytso-3s7WtUTddSA@public.gmane.org List-Id: dm-devel.ids On Tue, Oct 09, 2012 at 05:36:26PM -0700, Zach Brown wrote: > > The only situation you have to worry about is when the ringbuffer fills > > up and stuff goes on the list, and then completions completely stop - > > this should be a rare enough situation that maybe we could just hack > > around it with a timer that gets flipped on when the list isn't empty. > > Right. And this is when we hopefully realize that we're adding overhead > and complexity (how long's the timer? always fire it? MAKE IT STOP) > and are actually making the system worse, not better. Can still prototype it, and if it's that ugly... I throw away code all the time :P > > Also, for this to be an issue at all, _all_ the reaping would have to be > > done from userspace - since existing libaio doesn't do that, there may > > not be any code out there which triggers it. > > And there may be. We default to not breaking interfaces. Seriously. All the more reason to think about it now so we don't screw up the next interfaces :)