Messages in this thread | | | Subject | Re: [RFC][PATCH 00/16] sched: Core scheduling | From | Subhra Mazumdar <> | Date | Wed, 20 Feb 2019 18:53:08 -0800 |
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On 2/18/19 9:49 AM, Linus Torvalds wrote: > On Mon, Feb 18, 2019 at 9:40 AM Peter Zijlstra <peterz@infradead.org> wrote: >> However; whichever way around you turn this cookie; it is expensive and nasty. > Do you (or anybody else) have numbers for real loads? > > Because performance is all that matters. If performance is bad, then > it's pointless, since just turning off SMT is the answer. > > Linus I tested 2 Oracle DB instances running OLTP on a 2 socket 44 cores system. This is on baremetal, no virtualization. In all cases I put each DB instance in separate cpu cgroup. Following are the avg throughput numbers of the 2 instances. %stdev is the standard deviation between the 2 instances.
Baseline = build w/o CONFIG_SCHED_CORE core_sched = build w/ CONFIG_SCHED_CORE HT_disable = offlined sibling HT with baseline
Users Baseline %stdev core_sched %stdev HT_disable %stdev 16 997768 3.28 808193(-19%) 34 1053888(+5.6%) 2.9 24 1157314 9.4 974555(-15.8%) 40.5 1197904(+3.5%) 4.6 32 1693644 6.4 1237195(-27%) 42.8 1308180(-22.8%) 5.3
The regressions are substantial. Also noticed one of the DB instances was having much less throughput than the other with core scheduling which brought down the avg and also reflected in the very high %stdev. Disabling HT has effect at 32 users but still better than core scheduling both in terms of avg and %stdev. There are some issue with the DB setup for which I couldn't go beyond 32 users.
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