From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/1906 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: capset() capget() syscalls Date: Sun, 9 Sep 2012 16:14:01 -0400 Message-ID: <20120909201401.GG27715@brightrain.aerifal.cx> References: <20120905061905.GQ27715@brightrain.aerifal.cx> <50471B56.8040804@palsenberg.com> <20120905142441.GT27715@brightrain.aerifal.cx> <20120906030406.GY27715@brightrain.aerifal.cx> <20120907045631.GL27715@brightrain.aerifal.cx> <20120908221449.GZ27715@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1347221487 12539 80.91.229.3 (9 Sep 2012 20:11:27 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 9 Sep 2012 20:11:27 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-1907-gllmg-musl=m.gmane.org@lists.openwall.com Sun Sep 09 22:11:29 2012 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1TAnqp-0000Hi-7f for gllmg-musl@plane.gmane.org; Sun, 09 Sep 2012 22:11:27 +0200 Original-Received: (qmail 3229 invoked by uid 550); 9 Sep 2012 20:11:23 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 3221 invoked from network); 9 Sep 2012 20:11:23 -0000 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Xref: news.gmane.org gmane.linux.lib.musl.general:1906 Archived-At: On Sun, Sep 09, 2012 at 09:04:02PM +0100, Justin Cormack wrote: > On Sat, Sep 8, 2012 at 11:14 PM, Rich Felker wrote: > > Is there any legitimate user of this horrible API? Last I checked > > these functions were only useful for block-aligned IO on block devices > > and the impression I got was that they were designed solely for > > Oracle's use. (puke) I suppose they could be useful for FUSE drivers > > too, however. We can add them if they have legitimate software that > > needs them. > > It is still the only way to get decent io performance out of an SSD as > far as I can see, being about a factor of 8 faster than anything else > for random reads eg posix aio. Assuming of course our reads are block > aligned. If the normal Linux block cache system is even 25% slower than low-level IO on the device without any operating system at all, that's a major bug they need to fix. Adding hideous APIs to for userspace apps to do their own low-level IO is not a solution. 8x is just atrocious. Where does that figure come from? In fairness, if you're comparing to POSIX aio, that's a pretty bad API too. A thread performing standard blocking pread/pwrite should give the ideal performance. Rich