mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-06 10:58:48 +09:00
f9ab9bcf53
[ Upstream commit28156108fe] The commit2ebb177175("sched/core: Offload wakee task activation if it the wakee is descheduling") checked rq->nr_running <= 1 to avoid task stacking when WF_ON_CPU. Per the ordering of writes to p->on_rq and p->on_cpu, observing p->on_cpu (WF_ON_CPU) in ttwu_queue_cond() implies !p->on_rq, IOW p has gone through the deactivate_task() in __schedule(), thus p has been accounted out of rq->nr_running. As such, the task being the only runnable task on the rq implies reading rq->nr_running == 0 at that point. The benchmark result is in [1]. [1] https://lore.kernel.org/all/e34de686-4e85-bde1-9f3c-9bbc86b38627@linux.alibaba.com/ Suggested-by: Valentin Schneider <vschneid@redhat.com> Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <vschneid@redhat.com> Link: https://lore.kernel.org/r/20220608233412.327341-2-dtcccc@linux.alibaba.com Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.