From: Vlastimil Babka <vbabka@suse.cz>
To: Wei Yang <richard.weiyang@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
peterz@infradead.org, will@kernel.org, linyunsheng@huawei.com,
aarcange@redhat.com, feng.tang@intel.com, ebiederm@xmission.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: remove offset check on page->compound_head and folio->lru
Date: Tue, 25 Jan 2022 11:11:40 +0100 [thread overview]
Message-ID: <581f4247-83b1-df39-6724-af0565d0c7ea@suse.cz> (raw)
In-Reply-To: <20220124225531.26yyse52yo5x3fr5@master>
On 1/24/22 23:55, Wei Yang wrote:
> On Mon, Jan 24, 2022 at 11:30:10AM +0100, Vlastimil Babka wrote:
>>On 1/23/22 02:38, Wei Yang wrote:
>>> On Sat, Jan 08, 2022 at 08:13:40AM +0000, Wei Yang wrote:
>>>>On Sat, Jan 08, 2022 at 12:49:53AM +0000, Matthew Wilcox wrote:
>>>>>On Fri, Jan 07, 2022 at 04:08:25PM -0800, Andrew Morton wrote:
>>>>
>>>>To me, if folio has the same layout of page, folio meets this requirement. I
>>>>still not catch the point why we need this check here.
>>>>
>>>
>>> Hi, Matthew
>>>
>>> Are you back from vocation? If you could give more insight on this check, I
>>> would be appreciated.
>>
>>I can offer my insight (which might be of course wrong). Ideally one day
>>page.lru will be gone and only folio will be used for LRU pages. Then there
>>won't be a FOLIO_MATCH(lru, lru); and FOLIO_MATCH(compound_head, lru);
>>won't appear to be redundant anymore. lru is list_head so two pointers and
>
> Thanks for your comment.
>
> I can't imagine the final result. If we would remove page.lru, we could remove
> FOLIO_MATCH(lru, lru) and add FOLIO_MATCH(compound_head, lru) at that moment?
Yes, or we could forget to do it. Adding it right now is another option that
Matthew has chosen and I don't see a strong reason to change it. Can you
measure a kernel build speedup thanks to removing the now redundant check?
>>thus valid pointers are aligned in such a way they can't accidentaly set the
>>bit 0.
>>
>
next prev parent reply other threads:[~2022-01-25 10:15 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 23:52 [PATCH] mm: remove offset check on page->compound_head and folio->lru Wei Yang
2022-01-07 3:59 ` Matthew Wilcox
2022-01-07 13:40 ` Wei Yang
2022-01-07 22:11 ` Matthew Wilcox
2022-01-08 0:08 ` Andrew Morton
2022-01-08 0:49 ` Matthew Wilcox
2022-01-08 2:41 ` Andrew Morton
2022-01-08 8:13 ` Wei Yang
2022-01-23 1:38 ` Wei Yang
2022-01-24 10:30 ` Vlastimil Babka
2022-01-24 22:55 ` Wei Yang
2022-01-25 10:11 ` Vlastimil Babka [this message]
2022-01-27 1:10 ` Wei Yang
2022-01-27 15:42 ` Vlastimil Babka
2022-01-29 0:47 ` Wei Yang
2022-02-24 1:03 ` Wei Yang
2022-02-17 0:34 ` Wei Yang
2022-01-08 0:27 ` Wei Yang
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=581f4247-83b1-df39-6724-af0565d0c7ea@suse.cz \
--to=vbabka@suse.cz \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=ebiederm@xmission.com \
--cc=feng.tang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linyunsheng@huawei.com \
--cc=peterz@infradead.org \
--cc=richard.weiyang@gmail.com \
--cc=will@kernel.org \
--cc=willy@infradead.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.