From: Jake Moilanen Date: Tue, 25 Jul 2006 20:11:47 +0000 (-0500) Subject: [POWERPC] Use H_CEDE on non-SMT X-Git-Tag: v2.6.18-rc4~73^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9b9b72fe703bd5b89533815eb7eb682cdaf60a6e;p=linux-2.6 [POWERPC] Use H_CEDE on non-SMT On the JS21 systems, they have the SPLPAR hypertas set, but are not SMT capable. So, they are not making the H_CEDE call. This is causing the hypervisor to have to queue up work for the hdecr, taking an excessive amount of time in maintenance code, and causing jitter on the box. Making the H_CEDE call helps alleviate that problem. Signed-off-by: Jake Moilanen Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 54a5243726..71c634e0b8 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -501,7 +501,8 @@ static void pseries_dedicated_idle_sleep(void) } /* - * Cede if the other thread is not idle, so that it can + * If not SMT, cede processor. If CPU is running SMT + * cede if the other thread is not idle, so that it can * go single-threaded. If the other thread is idle, * we ask the hypervisor if it has pending work it * wants to do and cede if it does. Otherwise we keep @@ -514,7 +515,8 @@ static void pseries_dedicated_idle_sleep(void) * very low priority. The cede enables interrupts, which * doesn't matter here. */ - if (!lppaca[cpu ^ 1].idle || poll_pending() == H_PENDING) + if (!cpu_has_feature(CPU_FTR_SMT) || !lppaca[cpu ^ 1].idle + || poll_pending() == H_PENDING) cede_processor(); out: