From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zach Brown Subject: Re: [PATCH 4/5] aio: vmap ringbuffer Date: Tue, 9 Oct 2012 15:32:10 -0700 Message-ID: <20121009223210.GR26187@lenny.home.zabbo.net> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20121009213111.GE29494-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet 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: linux-bcache@vger.kernel.org > If it is measurable I'll take another stab at using memory from > __get_free_pages() for the ringbuffer. That really would be the ideal > solution. No, then you'll run into high order allocation failures with rings that don't fit in a single page. > The other reason I wanted to do this was for the aio attributes stuff - > for return values, I think the only sane way is for the return values to > go in the ringbuffer, which means records are no longer fixed size so > dealing with pages is even more of a pain. Then let's see that, please. And can we please stop calling them attributes? They're inputs and outputs that change behaviour -- they're interfaces. And no, just for the record, I don't think generic packed variable size structs are worth the trouble. If we're going to do a generic interface extension mechanism then we should put it in its own well thought out system calls, not staple it on to the side of aio because it's there. It's a really crummy base to work from. - z