linux-kernel - Re: [PATCH] btrfs: trimming some start

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Message-ID: <20150828173856.GM11834@twin.jikos.cz>
Date:	Fri, 28 Aug 2015 19:38:56 +0200
From:	David Sterba <dsterba@...e.cz>
To:	Alexandru Moise <00moses.alexander00@...il.com>
Cc:	clm@...com, jbacik@...com, dsterba@...e.com,
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs: trimming some start_transaction() code away

On Thu, Aug 27, 2015 at 11:53:45PM +0000, Alexandru Moise wrote:
> Just call kmem_cache_zalloc() instead of calling kmem_cache_alloc().
> We're just initializing most fields to 0, false and NULL later on
> _anyway_, so to make the code mode readable and potentially gain
> a bit of performance (completely untested claim), we should fill our
> btrfs_trans_handle with zeros on allocation then just initialize
> those five remaining fields (not counting the list_heads) as normal.
> 
> Signed-off-by: Alexandru Moise <00moses.alexander00@...il.com>

The performance gain is arguable but the generated code should be
smaller, which counts.

Reviewed-by: David Sterba <dsterba@...e.com>
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