On 07/06/2015 01:13 AM, Mike Galbraith wrote:
Hm. Piddling with pgbench, which doesn't seem to collapse into a
quivering heap when load exceeds cores these days, deltas weren't all
that impressive, but it does appreciate the extra effort a bit, and a
bit more when clients receive it as well.
If you test, and have time to piddle, you could try letting wake_wide()
return 1 + sched_feat(WAKE_WIDE_IDLE) instead of adding only if wakee is
the dispatcher.
Numbers from my little desktop box.
NO_WAKE_WIDE_IDLE
postgres@homer:~> pgbench.sh
clients 8 tps = 116697.697662
clients 12 tps = 115160.230523
clients 16 tps = 115569.804548
clients 20 tps = 117879.230514
clients 24 tps = 118281.753040
clients 28 tps = 116974.796627
clients 32 tps = 119082.163998 avg 117092.239 1.000
WAKE_WIDE_IDLE
postgres@homer:~> pgbench.sh
clients 8 tps = 124351.735754
clients 12 tps = 124419.673135
clients 16 tps = 125050.716498
clients 20 tps = 124813.042352
clients 24 tps = 126047.442307
clients 28 tps = 125373.719401
clients 32 tps = 126711.243383 avg 125252.510 1.069 1.000
WAKE_WIDE_IDLE (clients as well as server)
postgres@homer:~> pgbench.sh
clients 8 tps = 130539.795246
clients 12 tps = 128984.648554
clients 16 tps = 130564.386447
clients 20 tps = 129149.693118
clients 24 tps = 130211.119780
clients 28 tps = 130325.355433
clients 32 tps = 129585.656963 avg 129908.665 1.109 1.037
I have time for twiddling, we're carrying ye olde WAKE_IDLE until we get
this solved upstream and then I'll rip out the old and put in the new,
I'm happy to screw around until we're all happy. I'll throw this in a
kernel this morning and run stuff today. Barring any issues with the
testing infrastructure I should have results today. Thanks,
Josef
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