From: Boaz Harrosh <boaz@plexistor.com>
To: Hou Tao <houtao1@huawei.com>,
peterz@infradead.org, Oleg Nesterov <oleg@redhat.com>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Jan Kara <jack@suse.cz>
Subject: Re: [RFC PATCH] locking/percpu-rwsem: use this_cpu_{inc|dec}() for read_count
Date: Thu, 17 Sep 2020 13:51:43 +0300 [thread overview]
Message-ID: <ddd5d732-06da-f8f2-ba4a-686c58297e47@plexistor.com> (raw)
In-Reply-To: <b885ce8e-4b0b-8321-c2cc-ee8f42de52d4@huawei.com>
On 16/09/2020 15:32, Hou Tao wrote:
<>
> However the performance degradation is huge under aarch64 (4 sockets, 24 core per sockets): nearly 60% lost.
>
> v4.19.111
> no writer, reader cn | 24 | 48 | 72 | 96
> the rate of down_read/up_read per second | 166129572 | 166064100 | 165963448 | 165203565
> the rate of down_read/up_read per second (patched) | 63863506 | 63842132 | 63757267 | 63514920
>
I believe perhaps Peter Z's suggestion of an additional
percpu_down_read_irqsafe() API and let only those in IRQ users pay the
penalty.
Peter Z wrote:
> My leading alternative was adding: percpu_down_read_irqsafe() /
> percpu_up_read_irqsafe(), which use local_irq_save() instead of
> preempt_disable().
Thanks
Boaz
next prev parent reply other threads:[~2020-09-17 10:53 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 14:07 [RFC PATCH] locking/percpu-rwsem: use this_cpu_{inc|dec}() for read_count Hou Tao
2020-09-15 15:06 ` peterz
2020-09-15 15:31 ` Oleg Nesterov
2020-09-15 15:51 ` peterz
2020-09-15 16:03 ` peterz
2020-09-15 16:11 ` Will Deacon
2020-09-15 18:11 ` peterz
2020-09-16 8:20 ` Will Deacon
2020-09-15 16:47 ` Oleg Nesterov
2020-09-16 12:32 ` Hou Tao
2020-09-16 12:51 ` peterz
2020-09-17 8:48 ` Will Deacon
2020-09-24 11:55 ` Hou Tao
2020-09-29 17:49 ` Will Deacon
2020-09-29 18:07 ` Ard Biesheuvel
2020-09-17 10:51 ` Boaz Harrosh [this message]
2020-09-17 12:01 ` Oleg Nesterov
2020-09-17 12:48 ` Matthew Wilcox
2020-09-17 13:22 ` peterz
2020-09-17 13:34 ` Oleg Nesterov
2020-09-17 13:46 ` Boaz Harrosh
2020-09-17 14:46 ` Christoph Hellwig
2020-09-18 9:07 ` Jan Kara
2020-09-18 10:01 ` peterz
2020-09-18 10:04 ` peterz
2020-09-18 10:07 ` peterz
2020-09-18 10:12 ` peterz
2020-09-18 10:48 ` Oleg Nesterov
2020-09-18 11:03 ` peterz
2020-09-18 13:09 ` Oleg Nesterov
2020-09-18 13:26 ` Jan Kara
2020-09-20 23:49 ` Dave Chinner
2020-09-18 8:36 ` [tip: locking/urgent] locking/percpu-rwsem: Use this_cpu_{inc,dec}() " tip-bot2 for Hou Tao
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