Hello,
On Fri, 8 May 2015, Peter Zijlstra wrote:
> Subject: sched: Introduce TASK_NOLOAD and TASK_IDLE
> From: Peter Zijlstra <pet...@infradead.org>
> Date: Fri May 8 14:23:45 CEST 2015
>
> Currently people use TASK_INTERRUPTIBLE to idle kthreads and wait for
> 'work' because TASK_UNINTERRUPTIBLE contributes to the loadavg. Having
> all idle kthreads contribute to the loadavg is somewhat silly.
>
> Now mostly this works OK, because kthreads have all their signals
> masked. However there's a few sites where this is causing problems and
> TASK_UNINTERRUPTIBLE should be used, except for that loadavg issue.
>
> This patch adds TASK_NOLOAD which, when combined with
> TASK_UNINTERRUPTIBLE avoids the loadavg accounting.
>
> As most of imagined usage sites are loops where a thread wants to
> idle, waiting for work, a helper TASK_IDLE is introduced.
After checking our code in net/netfilter/ipvs/ip_vs_sync.c,
sync_thread_master(), we may also need some wrappers:
- schedule_timeout_idle (instead of schedule_timeout call):
__set_current_state(TASK_IDLE);
return schedule_timeout(timeout);
- we here are really idle, so "N" looks ok
- pair of __wait_event_idle(wq, condition) and
wait_event_idle(wq, condition) macros
- we here are write-blocked for socket, not sure
if this blocked vs idle difference is useful to
represent, in new bit for this blocked state "B"=2048,
with 2 TASK_NOLOAD variants: N(idle) and B(blocked,
2|1024|2048, eg. for read-blocked or write-blocked).
It will need additional argument 'state'/'blocked' for
*wait_event_idle().
Regards
--
Julian Anastasov <j...@ssi.bg>
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