From: shenghui <crosslonelyover@gmail.com>
Subject: Re: [PATCH] fix return value for mb_cache_shrink_fn when nr_to_scan >
	0
Date: Tue, 20 Jul 2010 09:02:57 +0800
Message-ID: <AANLkTimh4UjM3LWPjBjMA5UGecQYyPSxIvJBInijAP-j@mail.gmail.com>
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	<20100718060106.GA579@infradead.org>
	<4C42A10B.2080904@gmail.com>
	<201007192039.06670.agruen@suse.de>
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Cc: Christoph Hellwig <hch@infradead.org>, Eric Sandeen <sandeen@redhat.com>, linux-fsdevel@vger.kernel.org,
	viro@zeniv.linux.org.uk, linux-mm@kvack.org,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	kernel-janitors <kernel-janitors@vger.kernel.org>
To: Andreas Gruenbacher <agruen@suse.de>
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In-Reply-To: <201007192039.06670.agruen@suse.de>
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2010/7/20 Andreas Gruenbacher <agruen@suse.de>:
> On Sunday 18 July 2010 08:36:59 Wang Sheng-Hui wrote:
>> I regenerated the patch. Please check it.
>
> The logic for calculating how many objects to free is still wrong:
> mb_cache_shrink_fn returns the number of entries scaled by
> sysctl_vfs_cache_pressure / 100. =C2=A0It should also scale nr_to_scan by=
 the
> inverse of that. =C2=A0The sysctl_vfs_cache_pressure =3D=3D 0 case (never=
 scale) may
> require special attention.
>
> See dcache_shrinker() in fs/dcache.c.
>
> Thanks,
> Andreas
>

Sorry, I haven't found any special attention on
sysctl_vfs_cache_pressure =3D=3D 0 case or scale
nr_to_scan in fs/dcache.c

 900static int shrink_dcache_memory(int nr, gfp_t gfp_mask)
 901{
 902        if (nr) {
 903                if (!(gfp_mask & __GFP_FS))
 904                        return -1;
 905                prune_dcache(nr);
 906        }
 907        return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressur=
e;
 908}




--=20


Thanks and Best Regards,
shenghui

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