Messages in this thread | | | Date | Thu, 17 Mar 2022 16:08:04 +0100 | From | Frederic Weisbecker <> | Subject | Re: [patch v12 00/13] extensible prctl task isolation interface and vmstat sync |
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On Tue, Mar 15, 2022 at 12:31:32PM -0300, Marcelo Tosatti wrote: > The logic to disable vmstat worker thread, when entering > nohz full, does not cover all scenarios. For example, it is possible > for the following to happen: > > 1) enter nohz_full, which calls refresh_cpu_vm_stats, syncing the stats. > 2) app runs mlock, which increases counters for mlock'ed pages. > 3) start -RT loop > > Since refresh_cpu_vm_stats from nohz_full logic can happen _before_ > the mlock, vmstat shepherd can restart vmstat worker thread on > the CPU in question. > > To fix this, add task isolation prctl interface to quiesce > deferred actions when returning to userspace. > > The patchset is based on ideas and code from the > task isolation patchset from Alex Belits: > https://lwn.net/Articles/816298/ > > Please refer to Documentation/userspace-api/task_isolation.rst > (patch 1) for details. Its attached at the end of this message > in .txt format as well. > > Note: the prctl interface is independent of nohz_full=. > > The userspace patches can be found at https://people.redhat.com/~mtosatti/task-isol-v6-userspace-patches/ > > - qemu-task-isolation.patch: activate task isolation from CPU execution loop > - rt-tests-task-isolation.patch: add task isolation activation to cyclictest/oslat > - util-linux-chisol.patch: add chisol tool to util-linux.
I still see a few details to sort out but overall the whole thing looks good:
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Perhaps it's time to apply this patchset on some branch and iterate from there.
Thomas, Peter, what do you think?
Thanks!
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