From: Wei Yang <richard.weiyang@gmail.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Wei Yang <richard.weiyang@gmail.com>,
mhocko@kernel.org, vdavydov.dev@gmail.com,
akpm@linux-foundation.org, cgroups@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 3/3] mm/memcg: move generation assignment and comparison together
Date: Wed, 30 Mar 2022 23:04:29 +0000 [thread overview]
Message-ID: <20220330230429.ua5y42cgr3f6crnr@master> (raw)
In-Reply-To: <YkR902CHgavwleet@cmpxchg.org>
On Wed, Mar 30, 2022 at 11:57:07AM -0400, Johannes Weiner wrote:
>On Fri, Feb 25, 2022 at 12:34:37AM +0000, Wei Yang wrote:
>> For each round-trip, we assign generation on first invocation and
>> compare it on subsequent invocations.
>>
>> Let's move them together to make it more self-explaining. Also this
>> reduce a check on prev.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>
>This makes sense. The function is structured into 1) load state, 2)
>advance, 3) save state. The load state is a better fit for
>initializing reclaim->generation.
>
>> @@ -996,7 +996,14 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
>> mz = root->nodeinfo[reclaim->pgdat->node_id];
>> iter = &mz->iter;
>>
>> - if (prev && reclaim->generation != iter->generation)
>> + /*
>> + * On first invocation, assign iter->generation to
>> + * reclaim->generation.
>> + * On subsequent invocations, make sure no one else jump in.
>> + */
>> + if (!prev)
>> + reclaim->generation = iter->generation;
>> + else if (reclaim->generation != iter->generation)
>> goto out_unlock;
>
>The comment duplicates the code, it doesn't explain why we're doing
>this. How about:
>
> /*
> * On start, join the current reclaim iteration cycle.
> * Exit when a concurrent walker completes it.
> */
This one looks better and explain the reclaim model.
Thanks
>
>With that, please feel free to add:
>
>Acked-by: Johannes Weiner <hannes@cmpxchg.org>
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2022-03-30 23:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-25 0:34 [PATCH 0/3] mm/memcg: some cleanup for mem_cgroup_iter() Wei Yang
2022-02-25 0:34 ` [PATCH 1/3] mm/memcg: set memcg after css verified and got reference Wei Yang
2022-03-29 18:44 ` Johannes Weiner
2022-02-25 0:34 ` [PATCH 2/3] mm/memcg: set pos to prev unconditionally Wei Yang
2022-03-29 18:48 ` Johannes Weiner
2022-03-30 0:47 ` Wei Yang
2022-03-30 12:08 ` Johannes Weiner
2022-03-30 14:22 ` Wei Yang
2022-02-25 0:34 ` [PATCH 3/3] mm/memcg: move generation assignment and comparison together Wei Yang
2022-03-30 15:57 ` Johannes Weiner
2022-03-30 23:04 ` Wei Yang [this message]
2022-02-25 8:13 ` [PATCH 0/3] mm/memcg: some cleanup for mem_cgroup_iter() Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220330230429.ua5y42cgr3f6crnr@master \
--to=richard.weiyang@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=vdavydov.dev@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).