From mboxrd@z Thu Jan 1 00:00:00 1970 From: Muchun Song Subject: Re: [PATCH mm v2 3/9] memcg: enable accounting for kernfs iattrs Date: Sun, 22 May 2022 14:38:24 +0800 Message-ID: References: Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=63w6MmKKarIOHYX+K5PAEKcR1bSxb1g9RSGqBi4nt8U=; b=Wx+SmgtailJYnAhwvCnC+y1AuVwXo46QNLoLpoUb8rjVzBy5xo17x6lY2EmUp6sVHu l8rGunXcntC+8LTB0b38OVBedUWlQ47Xv+fYt8y2hIK2D9iH7/CRngOu9kSVBGc6TXFL 7RR9Zbl4Se+3YzKL9QmEf0AjB3Au30OSZlbshIcHneNizPzLdf4qfKySRtWPH6eV1RaD dCWHf2/vyiL69waPlmn2Ld3st9Y0kgrihwiSDETjrQ5145s8fQdluLTJ/0ltDMOY/OTR oRtt0ry2h3Xz7CDwMzplhnN0OtOJ3ZmREN/4PdnvTXgPq9UEFWaLcwwACBJihbNQeMim japQ== Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Vasily Averin Cc: Andrew Morton , kernel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Shakeel Butt , Roman Gushchin , Michal =?iso-8859-1?Q?Koutn=FD?= , Vlastimil Babka , Michal Hocko , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Sat, May 21, 2022 at 07:37:59PM +0300, Vasily Averin wrote: > kernfs nodes are quite small kernel objects, however there are few > scenarios where it consumes significant piece of all allocated memory: > > 1) creating a new netdevice allocates ~50Kb of memory, where ~10Kb > was allocated for 80+ kernfs nodes. > > 2) cgroupv2 mkdir allocates ~60Kb of memory, ~10Kb of them are kernfs > structures. > > 3) Shakeel Butt reports that Google has workloads which create 100s > of subcontainers and they have observed high system overhead > without memcg accounting of kernfs. > > Usually new kernfs node creates few other objects: > > Allocs Alloc Allocation > number size > -------------------------------------------- > 1 + 128 (__kernfs_new_node+0x4d) kernfs node > 1 + 88 (__kernfs_iattrs+0x57) kernfs iattrs > 1 + 96 (simple_xattr_alloc+0x28) simple_xattr, can grow over 4Kb > 1 32 (simple_xattr_set+0x59) > 1 8 (__kernfs_new_node+0x30) > > '+' -- to be accounted > > This patch enables accounting for kernfs_iattrs_cache slab cache > > Signed-off-by: Vasily Averin Reviewed-by: Muchun Song