From: Dave Chinner <david@fromorbit.com>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
peterz@infradead.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH] fs/dcache: optimize start_dir_add()
Date: Tue, 27 Oct 2020 08:59:23 +1100 [thread overview]
Message-ID: <20201026215923.GA306023@dread.disaster.area> (raw)
In-Reply-To: <20201022211650.25045-1-dave@stgolabs.net>
On Thu, Oct 22, 2020 at 02:16:50PM -0700, Davidlohr Bueso wrote:
> Considering both end_dir_add() and d_alloc_parallel(), the
> dir->i_dir_seq wants acquire/release semantics, therefore
> micro-optimize for ll/sc archs and use finer grained barriers
> to provide (load)-ACQUIRE ordering (L->S + L->L). This comes
> at no additional cost for most of x86, as sane tso models will
> have a nop for smp_rmb/smp_acquire__after_ctrl_dep.
>
> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
> ---
> Alternatively I guess we could just use cmpxchg_acquire().
Please us cmpxchg_acquire() so that people who have no clue what the
hell smp_acquire__after_ctrl_dep() means or does have some hope of
understanding of what objects the ordering semantics in the function
actually apply to....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2020-10-26 21:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 21:16 [PATCH] fs/dcache: optimize start_dir_add() Davidlohr Bueso
2020-10-26 21:59 ` Dave Chinner [this message]
2020-10-29 19:07 ` [PATCH v2] " Davidlohr Bueso
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