linux-kernel - Re: [PATCH v2] kernfs: Allocating memory for kernfs_iattrs with kmem

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Message-ID: <20190206163554.GI50184@devbig004.ftw2.facebook.com>
Date:   Wed, 6 Feb 2019 08:35:54 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Ayush Mittal <ayush.m@...sung.com>
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        pankaj.m@...sung.com, a.sahrawat@...sung.com, v.narang@...sung.com
Subject: Re: [PATCH v2] kernfs: Allocating memory for kernfs_iattrs with
 kmem_cache.

On Wed, Feb 06, 2019 at 10:25:42AM +0530, Ayush Mittal wrote:
> Creating a new cache for kernfs_iattrs.
> Currently, memory is allocated with kzalloc() which
> always gives aligned memory. On ARM, this is 64 byte aligned.
> To avoid the wastage of memory in aligning the size requested,
> a new cache for kernfs_iattrs is created.
> 
> Size of struct kernfs_iattrs is 80 Bytes.
> On ARM, it will come in kmalloc-128 slab.
> and it will come in kmalloc-192 slab if debug info is enabled.
> Extra bytes taken 48 bytes.
> 
> Total number of objects created : 4096
> Total saving = 48*4096 = 192 KB
> 
> After creating new slab(When debug info is enabled) :
> sh-3.2# cat /proc/slabinfo
> ...
> kernfs_iattrs_cache   4069   4096    128   32    1 : tunables    0    0    0 : slabdata    128    128      0
> ...
> 
> All testing has been done on ARM target.
> 
> Signed-off-by: Ayush Mittal <ayush.m@...sung.com>
> Signed-off-by: Vaneet Narang <v.narang@...sung.com>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun