From: Avi Kivity <avi@scylladb.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Peter Oskolkov <posk@google.com>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Boqun Feng <boqun.feng@gmail.com>, Andrew Hunter <ahh@google.com>,
Maged Michael <maged.michael@gmail.com>,
gromer@google.com,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [RFC PATCH 0/2] Introduce serialized smp_call_function APIs
Date: Wed, 13 Mar 2024 23:58:44 +0200 [thread overview]
Message-ID: <96325519f8f05d7289ec9b0af4e89da28c432e4f.camel@scylladb.com> (raw)
In-Reply-To: <20240313205622.2179659-1-mathieu.desnoyers@efficios.com>
[resend in plain text for the list]
On Wed, 2024-03-13 at 16:56 -0400, Mathieu Desnoyers wrote:
> commit 944d5fe50f3f ("sched/membarrier: reduce the ability to hammer
> on sys_membarrier")
> introduces a mutex over all membarrier operations to reduce its
> ability
> to slow down the rest of the system.
>
> This RFC series has two objectives:
>
> 1) Move this mutex to the smp_call_function APIs so other system
> calls
> using smp_call_function IPIs are limited in the same way,
>
> 2) Restore scalability of MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ with
> MEMBARRIER_CMD_FLAG_CPU, which targets specific CPUs with IPIs.
> This may or may not be useful, and I would welcome benchmarks from
> users of this feature to figure out if this is worth it.
>
I see this doesn't restore scaling of MEMBARRIER_CMD_PRIVATE_EXPEDITED,
which I use (and wasn't aware was broken).
I don't have comments on the patches, but do have ideas on how to work
around the problem in Seastar. So this was a useful heads-up for me.
next prev parent reply other threads:[~2024-03-13 21:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-13 20:56 Mathieu Desnoyers
2024-03-13 20:56 ` [RFC PATCH 1/2] smp: Implement " Mathieu Desnoyers
2024-03-13 21:19 ` Linus Torvalds
2024-03-13 23:24 ` Mathieu Desnoyers
2024-03-13 20:56 ` [RFC PATCH 2/2] sched/membarrier: Use " Mathieu Desnoyers
2024-03-13 21:58 ` Avi Kivity [this message]
[not found] ` <7c1860d783e0f317160069bf77d8fafdf01a9f97.camel@scylladb.com>
2024-03-13 22:06 ` [RFC PATCH 0/2] Introduce " Mathieu Desnoyers
2024-03-13 22:23 ` Avi Kivity
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