From: Andi Kleen <andi@firstfloor.org>
To: Vitaly Wool <vitalywool@gmail.com>
Cc: Linux-MM <linux-mm@kvack.org>,
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: Sat, 05 Nov 2016 16:38:22 -0700 [thread overview]
Message-ID: <87lgwxo5u9.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <20161105144946.3b4be0ee799ae61a82e1d918@gmail.com> (Vitaly Wool's message of "Sat, 5 Nov 2016 14:49:46 +0100")
Vitaly Wool <vitalywool@gmail.com> writes:
> Most of z3fold operations are in-page, such as modifying z3fold
> page header or moving z3fold objects within a page. Taking
> per-pool spinlock to protect per-page objects is therefore
> suboptimal, and the idea of having a per-page spinlock (or rwlock)
> has been around for some time. However, adding one directly to the
> z3fold header makes the latter quite big on some systems so that
> it won't fit in a signle chunk.
> + atomic_t page_lock;
This doesnt make much sense. A standard spinlock is not bigger
than 4 bytes either. Also reinventing locks is usually a bad
idea: they are tricky to get right, you have no debugging support,
hard to analyze, etc.
-Andi
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next prev parent reply other threads:[~2016-11-05 23:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-05 13:49 Vitaly Wool
2016-11-05 23:38 ` Andi Kleen [this message]
2016-11-06 9:42 ` Vitaly Wool
2016-11-07 16:06 ` Andi Kleen
2016-11-10 19:38 ` Peter Zijlstra
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