netdev - Re: [PATCH] prevent the read ahead of /proc/slabinfo in ss

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Message-ID: <1423498049.31870.192.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 09 Feb 2015 08:07:29 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Bryton Lee <brytonlee01@...il.com>
Cc:	stephen@...workplumber.org, netdev@...r.kernel.org
Subject: Re: [PATCH] prevent the read ahead of /proc/slabinfo in ss

On Mon, 2015-02-09 at 19:37 +0800, Bryton Lee wrote:
> ss reads ahead of /proc/slabinfo whatever slabstat will be used or not in future.
> this will cause huge system delay when the kernel hires SLAB allocator(SLUB allocator is ok). when program reads
> /proc/slabinfo, it will call s_show() in SLAB allocator level, and s_show() calls spin_lock_irq(&l3->list_lock) 
> then iterate on whole three lists. if one slab has about 900 million objects (for example dentry),
> it will cause more than 1000ms delay. 
> 
> so this patch prevents the read ahead of /proc/slabinfo, ss runs with most parameters not using slabstat at all.

Indeed, thanks !

Acked-by: Eric Dumazet <edumazet@...gle.com>


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