linux-kernel - RE: [PATCH] x86/resctrl: avoid compiler optimization in __resctrl_sched

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Date:   Fri, 3 Mar 2023 23:17:05 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     "Eranian, Stephane" <eranian@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "peterz@...radead.org" <peterz@...radead.org>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "peternewman@...gle.com" <peternewman@...gle.com>,
        "bp@...e.de" <bp@...e.de>,
        "james.morse@....com" <james.morse@....com>,
        "babu.moger@....com" <babu.moger@....com>,
        "ananth.narayan@....com" <ananth.narayan@....com>,
        "vschneid@...hat.com" <vschneid@...hat.com>
Subject: RE: [PATCH] x86/resctrl: avoid compiler optimization in
 __resctrl_sched_in

> However in the __switch_to() routine, the current point is changed.  If the
> compiler optimizes away the reload, then the resctrl_sched_in will look
> at the previous task instead of the new current task. This explains why we
> were not seeing the limit enforced on the benchmark.

Are there any other uses of "current" during context switch that might
be affected by this?

-Tony