On Wednesday 23 March 2005 18:09, Bodo Stroesser wrote: > [EMAIL PROTECTED] wrote: > > Use rep_nop instead of barrier for cpu_relax, following $(SUBARCH)'s > > doing that (i.e. i386 and x86_64). > > IIRC, Jeff had the idea, to use sched_yield() for this (from a discussion > on #uml). Hmm, makes sense, but this is to benchmark well... I remember from early discussions on 2.6 scheduler that using sched_yield might decrease performance (IIRC starve the calling application).
Also, that call should be put inside the idle loop, not for cpu_relax, which is very different, since it is used (for instance) in kernel/spinlock.c for spinlocks, and in such things. The "Pause" opcode is explicitly recommended (by Intel manuals, I don't recall why) for things like spinlock loops, and using yield there would be bad. > S390 does something similar using a special DIAG-opcode that > gives permission to zVM, that another Guest might run. > On a host running many UMLs, this might improve performance. > > So, I would like to have the small patch below (it's not tested, just an > idea). -- Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- This SF.net email is sponsored by Microsoft Mobile & Embedded DevCon 2005 Attend MEDC 2005 May 9-12 in Vegas. Learn more about the latest Windows Embedded(r) & Windows Mobile(tm) platforms, applications & content. Register by 3/29 & save $300 http://ads.osdn.com/?ad_id=6883&alloc_id=15149&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
