From mboxrd@z Thu Jan 1 00:00:00 1970 From: SF Markus Elfring Subject: Re: MD-RAID: Use seq_putc() in three status functions? Date: Mon, 17 Oct 2016 13:10:18 +0200 Message-ID: References: <566ABCD9.1060404@users.sourceforge.net> <786843ef-4b6f-eb04-7326-2f6f5b408826@users.sourceforge.net> <92c52f1d-d151-cea6-e9ac-31378e6862d0@users.sourceforge.net> <1475771699.1914.10.camel@perches.com> <77fb6fdc-7480-8607-0af1-42f73c125b9d@users.sourceforge.net> <688764a4-072d-2faf-37ba-a222b190a5d9@suse.de> <59d71170-c48d-a084-c748-b6ab74a2bee4@users.sourceforge.net> <1e151094-e228-5307-ae2f-b376b31f5628@suse.de> <83e720c6-9037-a3c1-6e83-27505805f37f@users.sourceforge.net> <2cc42b2f-1f1a-e95c-91fa-54e1dd3b6d49@suse.de> <653e60ee-f862-8828-3e4f-498c7cc34bdc@users.sourceforge.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Hannes Reinecke , linux-raid@vger.kernel.org Cc: Christoph Hellwig , Guoqing Jiang , Jens Axboe , Joe Perches , Mike Christie , Neil Brown , Shaohua Li , Tomasz Majchrzak , LKML , kernel-janitors@vger.kernel.org, kbuild-all@01.org, ltp@lists.linux.it List-Id: linux-raid.ids >> * Is a string pointer often longer than a byte? >> > Always. I have got doubts for this specific information. > (Which up to now I thought was basic programming knowledge...) By the way: Run time environments still exist where the size of a pointer can be also just one byte, don't they? >> How many results would we like to clarify from various hardware >> and software combinations? >> > See above. At the moment _any_ test result from your side would do. I imagine that another single result might not be representative. How many lessons from test statistics will usually be also relevant here? >> How important are the mentioned functions for you within the Linux >> programming interface so far? >> > Not very. The interface is only used in a slow path, and the execution > time doesn't affect I/O performance in any way. Thanks for another interesting information. >>> Case in point: with your patch the x86_64 compiler generates nearly >>> identical code for driver/md/raid1.c, but with one instruction _more_ >>> after your patch has been applied. >> >> Which software versions and command parameters did you try out >> for this information (from an unspecified run time environment)? >> > # gcc --version > gcc (SUSE Linux) 4.8.5 Thanks for this detail. * Did you choose any special optimisation settings for your quick check? * Will any compilation results matter if "optimisation" would be switched off there? > I'm still waiting from results from your side. Would any other software developers or testers dare to add related information? Regards, Markus