From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/2041 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: musl for ARM Date: Tue, 2 Oct 2012 09:48:43 -0400 Message-ID: <20121002134843.GV254@brightrain.aerifal.cx> References: Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1349186270 13471 80.91.229.3 (2 Oct 2012 13:57:50 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 2 Oct 2012 13:57:50 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-2042-gllmg-musl=m.gmane.org@lists.openwall.com Tue Oct 02 15:57:56 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 1TJ2yZ-0005ty-HM for gllmg-musl@plane.gmane.org; Tue, 02 Oct 2012 15:57:31 +0200 Original-Received: (qmail 26580 invoked by uid 550); 2 Oct 2012 13:57:25 -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 26572 invoked from network); 2 Oct 2012 13:57:25 -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:2041 Archived-At: On Tue, Oct 02, 2012 at 03:27:28PM +0800, Brian Wang wrote: > Hello all, > > I am currently thinking of switching to musl from glibc for my target > after some readings on musl. > I would like some advice from musl experts: > * Does it support gettext stuff? > * Does it _boost_ the performance on a 400MHz arm926 device? Or it > is just smaller? > By _boost_, I mean if the user can actually feel the improvement > in performance. In general, if an application's perceived performance varies heavily depending on libc, the application is probably doing something wrong or at least naive. I can think of some exceptions of course, but this advice is just to say that libc is probably not a place to look for significantly improving overall performance. If there are libc bottlenecks, you could probably get a lot more performance out of changing the application. The main exceptions I can think of are places where libc has the wrong big-O: for example, O(n²) qsort or O(nm) strstr, or backtracking regex implementations, can make completely-sane programs run extremely slow on a bad libc. Note that musl and glibc are almost always equivalent in this area; uclibc and dietlibc and perhaps others have some problems here. One area you can get vastly better performance with musl is application startup overhead. Especially with static linking, but even with dynamic linking if your only .so is libc, the startup time is 2-5x faster than glibc, which really makes a difference to the runtime of shell scripts (like configure) that invoke tons of external programs. > I did try the musl cross project and successfully built a musl-based > arm linux toolchain. > My kernel (2.6.24) was built successfully (not tried it on my device yet). > However, when building busybox, there are some header files clashes, > resulting in conflicting types. > An example of it: > --------------------- > In file included from > /opt/cross/arm-linux-musleabi/lib/gcc/arm-linux-musleabi/4.7.1/../../../../arm-linux-musleabi/include/linux/kd.h:3:0, > from console-tools/kbd_mode.c:23: > /opt/cross/arm-linux-musleabi/lib/gcc/arm-linux-musleabi/4.7.1/../../../../arm-linux-musleabi/include/linux/types.h:12:26: > error: conflicting types for ‘fd_set’ > In file included from > /opt/cross/arm-linux-musleabi/lib/gcc/arm-linux-musleabi/4.7.1/../../../../arm-linux-musleabi/include/sys/time.h:9:0, > from include/libbb.h:45, > from console-tools/kbd_mode.c:22: > /opt/cross/arm-linux-musleabi/lib/gcc/arm-linux-musleabi/4.7.1/../../../../arm-linux-musleabi/include/sys/select.h:25:3: > note: previous declaration of ‘fd_set’ was here > --------------------- It looks like these kernel headers are not sanitized for compatibility with userspace..? Rich