Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps -11.3% regression

From	Mike Galbraith <efault@gmx.de>
Newsgroups	linux.kernel
Subject	Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps -11.3% regression
Date	2017-09-11 05:00 +0200
Message-ID	<uon73-4Ue-3@gated-at.bofh.it> (permalink)
References	<uiUfn-nC-1@gated-at.bofh.it> <uoaMx-4sT-3@gated-at.bofh.it> <uodKq-6F7-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Sun, 2017-09-10 at 09:53 -0700, Joel Fernandes wrote:
> 
> Anyone know what in the netperf test triggers use of the sync flag?

homer:..kernel/linux-master # git grep wake_up_interruptible_sync_poll net
net/core/sock.c:                wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI |
net/core/sock.c:                        wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
net/sctp/socket.c:              wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
net/smc/smc_rx.c:               wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI |
net/tipc/socket.c:              wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
net/tipc/socket.c:              wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
net/unix/af_unix.c:                     wake_up_interruptible_sync_poll(&wq->wait,
net/unix/af_unix.c:             wake_up_interruptible_sync_poll(&u->peer_wait,

The same as metric tons of other stuff.

Once upon a time, we had avg_overlap to help decide whether to wake
core affine or not, on top of the wake_affine() imbalance constraint,
but instrumentation showed it to be too error prone, so it had to die.
 These days, an affine wakeup generally means cache affine, and the
sync hint gives you a wee bit more chance of migration near to tasty
hot data being approved.

The sync hint was born back in the bad old days, when communicating
tasks not sharing L2 may as well have been talking over two tin cans
and a limp string.  These days, things are oodles better, but truly
synchronous stuff could still benefit from core affinity (up to hugely
for very fast/light stuff) if it weren't for all the caveats that can
lead to tossing concurrency opportunities out the window.

	-Mike

Thread

[PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Joel Fernandes <joelaf@google.com> - 2017-08-27 03:10 +0200
  Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-27 07:50 +0200
    Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-27 08:10 +0200
      Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Joel Fernandes <joelaf@google.com> - 2017-08-27 08:40 +0200
        Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-27 09:20 +0200
        Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-27 20:10 +0200
          Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Joel Fernandes <joelaf@google.com> - 2017-08-28 07:30 +0200
            Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-28 08:20 +0200
              Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-28 08:50 +0200
              Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Joel Fernandes <joelaf@google.com> - 2017-08-28 18:30 +0200
                Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-28 19:20 +0200
    Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Joel Fernandes <joelaf@google.com> - 2017-08-27 08:30 +0200
    Re: [PATCH RFC/RFT] sched/fair: Improve the behavior of sync flag Mike Galbraith <efault@gmx.de> - 2017-08-27 09:00 +0200
  Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Joel Fernandes <joelaf@google.com> - 2017-09-10 19:00 +0200
    Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Mike Galbraith <efault@gmx.de> - 2017-09-11 05:00 +0200
      Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Joel Fernandes <joelaf@google.com> - 2017-09-11 08:40 +0200
        Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Mike Galbraith <efault@gmx.de> - 2017-09-11 10:10 +0200
        Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Rik van Riel <riel@redhat.com> - 2017-09-14 18:00 +0200
          Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Mike Galbraith <efault@gmx.de> - 2017-09-15 06:10 +0200
          Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Joel Fernandes <joelaf@google.com> - 2017-09-17 08:50 +0200
            Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Mike Galbraith <efault@gmx.de> - 2017-09-17 18:50 +0200
              Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Joel Fernandes <joelaf@google.com> - 2017-09-17 23:50 +0200
                Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Mike Galbraith <efault@gmx.de> - 2017-09-18 07:40 +0200
                Re: [lkp-robot] [sched/fair] 6d46bd3d97: netperf.Throughput_tps  -11.3% regression Joel Fernandes <joelaf@google.com> - 2017-09-25 01:50 +0200

csiph-web