On Thursday 15 March 2007 13:31, Siddha, Suresh B wrote: > Con, > > On Mon, Mar 12, 2007 at 10:58:11AM +1100, Con Kolivas wrote: > > There are updated patches for 2.6.20, 2.6.20.2, 2.6.21-rc3 and > > 2.6.21-rc3-mm2 to bring RSDL up to version 0.30 for download here: > > I tried this on a Core 2 Quad cpu system(system has 4 cores on a single > package). When I run SPECjbb2000 with number of threads varying from 1-8, > I see ~4.5% perf regression with RSDL (compared to native 2.6.21-rc3) in > the 8 threads case. This I think, is coming from increased number of > context switches, when we have more than one thread(at same user priority) > on the same logical cpu. > > Just to see the % increase in number of context switches, I ran 8 infinite > loops (simple while(1); 's) and with 2.6.21-rc3 I see ~70 context switches > every second, whereas with RSDL I see ~530 context switches.
Thanks. If it's just that then scaling rr interval with cpus somewhat would help. If you could, the following patch just to test might confirm that. --- kernel/sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6.21-rc3-mm2/kernel/sched.c =================================================================== --- linux-2.6.21-rc3-mm2.orig/kernel/sched.c 2007-03-15 17:03:17.000000000 +1100 +++ linux-2.6.21-rc3-mm2/kernel/sched.c 2007-03-15 17:03:30.000000000 +1100 @@ -104,7 +104,7 @@ unsigned long long __attribute__((weak)) * This is the time all tasks within the same priority round robin. * Set to a minimum of 6ms. */ -#define RR_INTERVAL ((6 * HZ / 1001) + 1) +#define RR_INTERVAL ((12 * HZ / 1001) + 1) #define DEF_TIMESLICE (RR_INTERVAL * 20) #ifdef CONFIG_SMP -- -ck - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
