From: Shakeel Butt <shakeel.butt@linux.dev>
To: Yosry Ahmed <yosryahmed@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/7] memcg: reduce memory size of mem_cgroup_events_index
Date: Fri, 26 Apr 2024 18:15:14 -0700 [thread overview]
Message-ID: <lyxw3jphvncnfgenvpocl2srs2vtm4frmv7yyieel544apwaub@mrddepkseafr> (raw)
In-Reply-To: <CAJD7tkYsz+v9z=3N3dCUFP-9L3RazVkQU_6Cuy0o8-0Ouq-S5g@mail.gmail.com>
On Fri, Apr 26, 2024 at 05:42:48PM -0700, Yosry Ahmed wrote:
> On Fri, Apr 26, 2024 at 5:37 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
> >
> > mem_cgroup_events_index is a translation table to get the right index of
> > the memcg relevant entry for the general vm_event_item. At the moment,
> > it is defined as integer array. However on a typical system the max
> > entry of vm_event_item (NR_VM_EVENT_ITEMS) is 113, so we don't need to
> > use int as storage type of the array. For now just use int8_t as type
> > and add a BUILD_BUG_ON() and will switch to short once NR_VM_EVENT_ITEMS
> > touches 127.
>
> Any reason not to use uint8_t (or simply u8) and U8_MAX (instead of
> the hardcoded 127)?
>
Just to keep the error check simple i.e. (index < 0). If we hit 127 then
we can switch to uint8_t and S8_MAX as error. Though 127 should be
replaced by S8_MAX. Somehow I was grep'ing for INT8*MAX variants.
Anyways if there is more support for uint8_t, I will change otherwise I
will keep as is.
next prev parent reply other threads:[~2024-04-27 1:15 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-27 0:37 [PATCH v2 0/7] memcg: reduce memory consumption by memcg stats Shakeel Butt
2024-04-27 0:37 ` [PATCH v2 1/7] memcg: reduce memory size of mem_cgroup_events_index Shakeel Butt
2024-04-27 0:42 ` Yosry Ahmed
2024-04-27 1:15 ` Shakeel Butt [this message]
2024-04-29 15:36 ` Roman Gushchin
2024-04-27 0:37 ` [PATCH v2 2/7] memcg: dynamically allocate lruvec_stats Shakeel Butt
2024-04-27 1:23 ` Yosry Ahmed
2024-04-29 15:50 ` Roman Gushchin
2024-04-29 19:46 ` Shakeel Butt
2024-04-29 21:02 ` Roman Gushchin
2024-04-29 21:59 ` Shakeel Butt
2024-04-27 0:37 ` [PATCH v2 3/7] memcg: reduce memory for the lruvec and memcg stats Shakeel Butt
2024-04-27 0:51 ` Yosry Ahmed
2024-04-27 1:16 ` Shakeel Butt
2024-04-27 1:18 ` Yosry Ahmed
2024-04-29 16:00 ` Roman Gushchin
2024-04-29 20:00 ` Shakeel Butt
2024-04-29 17:35 ` T.J. Mercier
2024-04-29 20:13 ` Shakeel Butt
2024-04-29 22:23 ` T.J. Mercier
2024-04-27 0:37 ` [PATCH v2 4/7] memcg: cleanup __mod_memcg_lruvec_state Shakeel Butt
2024-04-27 0:53 ` Yosry Ahmed
2024-04-29 15:45 ` Roman Gushchin
2024-04-27 0:37 ` [PATCH v2 5/7] memcg: pr_warn_once for unexpected events and stats Shakeel Butt
2024-04-27 0:58 ` Yosry Ahmed
2024-04-27 1:18 ` Shakeel Butt
2024-04-27 14:22 ` Johannes Weiner
2024-04-29 19:54 ` Shakeel Butt
2024-04-29 16:06 ` Roman Gushchin
2024-04-29 19:56 ` Shakeel Butt
2024-04-27 0:37 ` [PATCH v2 6/7] memcg: use proper type for mod_memcg_state Shakeel Butt
2024-04-27 0:37 ` [PATCH v2 7/7] mm: cleanup WORKINGSET_NODES in workingset Shakeel Butt
2024-04-29 16:07 ` Roman Gushchin
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