From: Andi Kleen <andi@firstfloor.org>
To: Vitaly Wool <vitalywool@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>, Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Dan Streetman <ddstreet@ieee.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH/RFC] z3fold: use per-page read/write lock
Date: Mon, 7 Nov 2016 08:06:53 -0800 [thread overview]
Message-ID: <20161107160652.GJ26852@two.firstfloor.org> (raw)
In-Reply-To: <CAMJBoFNWV92c5B3HLJ=6wgNNUJFpTUgu3qf1mWgYxTEhfaA_LA@mail.gmail.com>
> I understand the reinvention part but you're not quite accurate here
> with the numbers.
>
> E. g. on x86_64:
> (gdb) p sizeof(rwlock_t)
> $1 = 8
I was talking about spinlocks which are 4 bytes. Just use a spinlock then.
rwlocks are usually a bad idea anyways because they often scale far worse than
spinlocks due to the bad cache line bouncing behavior, and it doesn't
make much difference unless your critical section is very long.
-Andi
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next prev parent reply other threads:[~2016-11-07 16:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-05 13:49 [PATCH/RFC] z3fold: use per-page read/write lock Vitaly Wool
2016-11-05 23:38 ` Andi Kleen
2016-11-06 9:42 ` Vitaly Wool
2016-11-07 16:06 ` Andi Kleen [this message]
2016-11-10 19:38 ` Peter Zijlstra
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