From: Peter Zijlstra <peterz@infradead.org>
To: Rik van Riel <riel@surriel.com>
Cc: Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com,
luto@kernel.org, tglx@linutronix.de, mingo@redhat.com,
x86@kernel.org, kernel-team@meta.com, hpa@zytor.com,
bigeasy@linutronix.de
Subject: Re: [PATCh 0/3] x86,tlb: context switch optimizations
Date: Thu, 14 Nov 2024 15:40:07 +0100 [thread overview]
Message-ID: <20241114144007.GB39245@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <cdba614a4522307fb06615fcc3909f2f2d03f333.camel@surriel.com>
On Thu, Nov 14, 2024 at 09:27:25AM -0500, Rik van Riel wrote:
> 1) Move the interrupt re-enabling up (probably not this one?)
Correct, that one is wrong for it results in IPIs that we don't want or
need.
> 2) Explicitly clear the mm_cpumask bit in unuse_temporary_mm()
>
> 3) Have unuse_temporary_mm increment the mm's tlb_gen, since that
> is the only thing flush_tlb_mm_range really does for an MM
> without any bits set in the mm_cpumask.
So flush_tlb_mm_range() has an 'mm == loaded_mm' case, which does a
local flush. I *think* we're not hitting that because switch_mm() does a
write to loaded_mm() just before this.
But I don't think we want to proliferate the logic contained in
flush_tlb_mm_range() further than we have to.
So my preference goes to 2, as that seems to be the safest option.
Notably text_poke() it not concerned with performance much.
next prev parent reply other threads:[~2024-11-14 14:40 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-09 0:27 Rik van Riel
2024-11-09 0:27 ` [PATCH 1/3] x86,tlb: update mm_cpumask lazily Rik van Riel
2024-11-13 2:59 ` [tip: x86/mm] x86/mm/tlb: Update " tip-bot2 for Rik van Riel
2024-11-09 0:27 ` [PATCH 2/3] x86,tlb: add tracepoint for TLB flush IPI to stale CPU Rik van Riel
2024-11-13 2:59 ` [tip: x86/mm] x86/mm/tlb: Add " tip-bot2 for Rik van Riel
2024-11-09 0:27 ` [PATCH 3/3] x86,tlb: put cpumask_test_cpu in prev == next under CONFIG_DEBUG_VM Rik van Riel
2024-11-13 2:59 ` [tip: x86/mm] x86/mm/tlb: Put cpumask_test_cpu() check in switch_mm_irqs_off() " tip-bot2 for Rik van Riel
2024-11-13 9:55 ` [PATCh 0/3] x86,tlb: context switch optimizations Borislav Petkov
2024-11-13 10:00 ` Ingo Molnar
2024-11-13 14:38 ` Rik van Riel
2024-11-14 11:33 ` Peter Zijlstra
2024-11-13 14:55 ` Rik van Riel
2024-11-14 9:52 ` Ingo Molnar
2024-11-14 11:36 ` Peter Zijlstra
2024-11-14 14:27 ` Rik van Riel
2024-11-14 14:40 ` Peter Zijlstra [this message]
2024-11-14 11:36 ` Peter Zijlstra
2024-11-14 11:43 ` Peter Zijlstra
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