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From: Vlastimil Babka <vbabka@suse.cz>
To: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	linux-mm@kvack.org, kernel-team@fb.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 03/19] mm: memcg: convert vmstat slab counters to bytes
Date: Thu, 21 May 2020 11:57:12 +0200	[thread overview]
Message-ID: <21975f76-f58f-14ef-9547-7e32afac1681@suse.cz> (raw)
In-Reply-To: <20200520192652.GA278395@carbon.dhcp.thefacebook.com>

On 5/20/20 9:26 PM, Roman Gushchin wrote:
> On Wed, May 20, 2020 at 02:25:22PM +0200, Vlastimil Babka wrote:
>> 
>> However __mod_node_page_state() and mode_node_state() will now branch always. I
>> wonder if the "API clean" goal is worth it...
> 
> You mean just adding a special write-side helper which will perform a conversion
> and put VM_WARN_ON_ONCE() into generic write-side helpers?

What I mean is that maybe node/global helpers should assume page granularity,
and lruvec/memcg helpers do the check is they should convert from bytes to pages
when calling node/global helpers. Then there would be no extra branches in
node/global helpers. But maybe it's not worth saving those branches, dunno.

>> 
>> > --- a/mm/memcontrol.c
>> > +++ b/mm/memcontrol.c
>> > @@ -1409,9 +1409,8 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
>> >  		       (u64)memcg_page_state(memcg, MEMCG_KERNEL_STACK_KB) *
>> >  		       1024);
>> >  	seq_buf_printf(&s, "slab %llu\n",
>> > -		       (u64)(memcg_page_state(memcg, NR_SLAB_RECLAIMABLE) +
>> > -			     memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE)) *
>> > -		       PAGE_SIZE);
>> > +		       (u64)(memcg_page_state(memcg, NR_SLAB_RECLAIMABLE_B) +
>> > +			     memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE_B)));
>> >  	seq_buf_printf(&s, "sock %llu\n",
>> >  		       (u64)memcg_page_state(memcg, MEMCG_SOCK) *
>> >  		       PAGE_SIZE);
>> > @@ -1445,11 +1444,9 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
>> >  			       PAGE_SIZE);
>> >  
>> >  	seq_buf_printf(&s, "slab_reclaimable %llu\n",
>> > -		       (u64)memcg_page_state(memcg, NR_SLAB_RECLAIMABLE) *
>> > -		       PAGE_SIZE);
>> > +		       (u64)memcg_page_state(memcg, NR_SLAB_RECLAIMABLE_B));
>> >  	seq_buf_printf(&s, "slab_unreclaimable %llu\n",
>> > -		       (u64)memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE) *
>> > -		       PAGE_SIZE);
>> > +		       (u64)memcg_page_state(memcg, NR_SLAB_UNRECLAIMABLE_B));
>> 
>> So here we are now printing in bytes instead of pages, right? That's fine for
>> OOM report, but in sysfs aren't we breaking existing users?
>> 
> 
> Hm, but it was in bytes previously, look at that x * PAGE_SIZE.

Yeah, that's what I managed to overlook, sorry.

> Or do you mean that now it can be not rounded to PAGE_SIZE?
> If so, I don't think it breaks any expectations.
> 
> Thanks!
> 


  reply	other threads:[~2020-05-21  9:57 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-22 20:46 [PATCH v3 00/19] The new cgroup slab memory controller Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state() Roman Gushchin
2020-05-07 20:33   ` Johannes Weiner
2020-05-20 10:49   ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 02/19] mm: memcg: prepare for byte-sized vmstat items Roman Gushchin
2020-05-07 20:34   ` Johannes Weiner
2020-05-20 11:31   ` Vlastimil Babka
2020-05-20 11:36     ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 03/19] mm: memcg: convert vmstat slab counters to bytes Roman Gushchin
2020-05-07 20:41   ` Johannes Weiner
2020-05-20 12:25   ` Vlastimil Babka
2020-05-20 19:26     ` Roman Gushchin
2020-05-21  9:57       ` Vlastimil Babka [this message]
2020-05-21 21:14         ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 04/19] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-04-22 23:52   ` Christopher Lameter
2020-04-22 23:52     ` Christopher Lameter
2020-04-23  0:05     ` Roman Gushchin
2020-04-25  2:10       ` Christopher Lameter
2020-04-25  2:10         ` Christopher Lameter
2020-04-25  2:46         ` Roman Gushchin
2020-04-27 16:21           ` Christopher Lameter
2020-04-27 16:21             ` Christopher Lameter
2020-04-27 16:46             ` Roman Gushchin
2020-04-28 17:06               ` Roman Gushchin
2020-04-28 17:45               ` Johannes Weiner
2020-04-30 16:29               ` Christopher Lameter
2020-04-30 16:29                 ` Christopher Lameter
2020-04-30 17:15                 ` Roman Gushchin
2020-05-02 23:54                   ` Christopher Lameter
2020-05-02 23:54                     ` Christopher Lameter
2020-05-04 18:29                     ` Roman Gushchin
2020-05-08 21:35                       ` Christopher Lameter
2020-05-08 21:35                         ` Christopher Lameter
2020-05-13  0:57                         ` Roman Gushchin
2020-05-15 21:45                           ` Christopher Lameter
2020-05-15 21:45                             ` Christopher Lameter
2020-05-15 22:12                             ` Roman Gushchin
2020-05-20  9:51                           ` Vlastimil Babka
2020-05-20 20:57                             ` Roman Gushchin
2020-05-15 20:02                         ` Roman Gushchin
2020-04-23 21:01     ` Roman Gushchin
2020-04-25  2:10       ` Christopher Lameter
2020-04-25  2:10         ` Christopher Lameter
2020-05-20 13:51   ` Vlastimil Babka
2020-05-20 21:00     ` Roman Gushchin
2020-05-21 11:01       ` Vlastimil Babka
2020-05-21 21:06         ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 06/19] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-05-07 21:03   ` Johannes Weiner
2020-05-07 22:26     ` Roman Gushchin
2020-05-12 22:56       ` Johannes Weiner
2020-05-15 22:01         ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-04-23 20:20   ` Roman Gushchin
2020-05-22 18:27   ` Vlastimil Babka
2020-05-23  1:32     ` Roman Gushchin
2020-05-26 17:50     ` Roman Gushchin
2020-05-25 14:46   ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 08/19] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-05-25 15:07   ` Vlastimil Babka
2020-05-26 17:53     ` Roman Gushchin
2020-05-27 11:03       ` Vlastimil Babka
2020-04-22 20:46 ` [PATCH v3 09/19] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-05-25 16:10   ` Vlastimil Babka
2020-05-26 18:04     ` Roman Gushchin
2020-04-22 20:46 ` [PATCH v3 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-05-07 21:05   ` Johannes Weiner
2020-04-22 20:47 ` [PATCH v3 11/19] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-05-25 17:03   ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 12/19] mm: memcg/slab: use a single set of kmem_caches for all accounted allocations Roman Gushchin
2020-05-26 10:12   ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 13/19] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-05-26 10:31   ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 14/19] mm: memcg/slab: deprecate memcg_kmem_get_cache() Roman Gushchin
2020-05-26 10:34   ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 15/19] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-05-26 10:52   ` Vlastimil Babka
2020-05-26 18:50     ` Roman Gushchin
2020-04-22 20:47 ` [PATCH v3 16/19] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-05-26 11:31   ` Vlastimil Babka
2020-04-22 20:47 ` [PATCH v3 17/19] mm: memcg/slab: use a single set of kmem_caches for all allocations Roman Gushchin
2020-05-26 14:55   ` Vlastimil Babka
2020-05-27  8:35     ` Jesper Dangaard Brouer
2020-04-22 20:47 ` [PATCH v3 18/19] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-05-26 15:24   ` Vlastimil Babka
2020-05-26 15:45     ` Roman Gushchin
2020-05-27 17:00       ` Vlastimil Babka
2020-05-27 20:45         ` Roman Gushchin
2020-04-22 20:47 ` [PATCH v3 19/19] tools/cgroup: add memcg_slabinfo.py tool Roman Gushchin
2020-05-05 15:59   ` Tejun Heo

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