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authorIngo Molnar <mingo@elte.hu>2008-11-08 10:19:55 -0500
committerIngo Molnar <mingo@elte.hu>2008-11-08 10:48:19 -0500
commit0d12cdd5f883f508d33b85c1bae98fa28987c8c7 (patch)
treee07bb1f9ef49062fbd9817fe41cab66964bedf03 /arch/s390
parent52c642f33b14bfa1b00ef2b68296effb34a573f3 (diff)
sched: improve sched_clock() performance
in scheduler-intense workloads native_read_tsc() overhead accounts for 20% of the system overhead: 659567 system_call 41222.9375 686796 schedule 435.7843 718382 __switch_to 665.1685 823875 switch_mm 4526.7857 1883122 native_read_tsc 55385.9412 9761990 total 2.8468 this is large part due to the rdtsc_barrier() that is done before and after reading the TSC. But sched_clock() is not a precise clock in the GTOD sense, using such barriers is completely pointless. So remove the barriers and only use them in vget_cycles(). This improves lat_ctx performance by about 5%. Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/s390')
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