From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Date: Mon, 12 Jul 2004 19:15:51 +0000 Subject: Re: Timer patches (nsec support + fastcalls for gettod/clock_gettime for all clocks) Message-Id: <200407121215.51266.clameter@sgi.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Have been working on the asm portion in the last days and also saw some strange things that could explain your problems (a segfault caused by clock_gettime and problems with seqlock handling). Will post another version later. Thanks for the evaluation. On Monday 12 July 2004 10:45 am, Chen, Kenneth W wrote: > Christoph Lameter wrote on Friday, July 09, 2004 3:58 PM > > > The following patch is the first edition that is complete in that it > > provides all existing functionality (fastcalls) and enhances various > > interfaces: > > > > 1. Restructure timer interpolators to extract common code and provide a > > structure that can be used from assembly language. > > 2. Remove cmpxchg that causes scalability problems (for all clocks > > including ITC now) > > > > 3. Simplify gettimeofday > > > > 4. Provide new fastcall gettimeofday suitable for all types of clock > > (including cyclone and SN2 RTC). More than factor 10 speed gain on > > machines that did not use ITC clock before. > > > > 5. Provide fastcall path for clock_gettime(CLOCK_REALTIME). Also for all > > clock times. More than a factor 20 gain on this one since it returns > > nanoseconds resolution and thereby avoids the multiplications / division > > and the syscall overhead. > > > > 6. nanosecond resolution for CLOCK_REALTIME and CLOCK_MONOTONIC. This > > yield a 40ns resolution on SN2. > > > > Todo: > > - Test with cyclone machines > > - Test with machines that only have ITC based clocks. > > > > Testind and feedback appreciated. > > The C portion works pretty well on ITC based clock. One java benchmark > that uses gettimeofday heavily gained one percentage point. The assembly > portion of the fsys call need some more work though, mingetty from the > boot init script falls flat upon booting this patch. > > - Ken