From: Vlastimil Babka <vbabka@suse.cz>
To: Alex Shi <alex.shi@linux.alibaba.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>,
Hugh Dickins <hughd@google.com>, Yu Zhao <yuzhao@google.com>,
Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH next] mm/vmscan: __isolate_lru_page_prepare clean up
Date: Thu, 26 Nov 2020 16:23:42 +0100 [thread overview]
Message-ID: <2ba66325-e3c8-d809-a8dd-85af77c3904b@suse.cz> (raw)
In-Reply-To: <ebbad64b-069a-26e0-ac0a-854649e20a97@linux.alibaba.com>
On 11/26/20 3:25 AM, Alex Shi wrote:
>
>
> 在 2020/11/26 上午7:43, Andrew Morton 写道:
>> On Tue, 24 Nov 2020 12:21:28 +0100 Vlastimil Babka <vbabka@suse.cz> wrote:
>>
>>> On 11/22/20 3:00 PM, Alex Shi wrote:
>>>> Thanks a lot for all comments, I picked all up and here is the v3:
>>>>
>>>> From 167131dd106a96fd08af725df850e0da6ec899af Mon Sep 17 00:00:00 2001
>>>> From: Alex Shi <alex.shi@linux.alibaba.com>
>>>> Date: Fri, 20 Nov 2020 14:49:16 +0800
>>>> Subject: [PATCH v3 next] mm/vmscan: __isolate_lru_page_prepare clean up
>>>>
>>>> The function just return 2 results, so use a 'switch' to deal with its
>>>> result is unnecessary, and simplify it to a bool func as Vlastimil
>>>> suggested.
>>>>
>>>> Also remove 'goto' by reusing list_move(), and take Matthew Wilcox's
>>>> suggestion to update comments in function.
>>>
>>> I wouldn't mind if the goto stayed, but it's not repeating that much
>>> without it (list_move() + continue, 3 times) so...
>>
>> I tried that, and .text became significantly larger, for reasons which
>> I didn't investigate ;)
I found out that comparing whole .text doesn't often work as changes might be lost in alignment, or
once in a while cross the alignment boundary and become exagerated. bloat-o-meter works nice though.
> Uh, BTW, with the gcc 8.3.1 and centos 7, goto or continue version has same size
> on my side with or w/o DEBUG_LIST. But actually, this clean up patch could
> add 10 bytes also with or w/o DEDBUG_LIST.
>
> Maybe related with different compiler?
gcc (SUSE Linux) 10.2.1 20201117 [revision 98ba03ffe0b9f37b4916ce6238fad754e00d720b]
./scripts/bloat-o-meter vmscan.o.before mm/vmscan.o
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-1 (-1)
Function old new delta
isolate_lru_pages 1125 1124 -1
Total: Before=57283, After=57282, chg -0.00%
Not surprising, as I'd expect the compiler to figure out by itself that list_move + continue
repeats and can be unified. The reason for goto to stay would be rather readability (subjective).
> Thanks
> Alex
>
next prev parent reply other threads:[~2020-11-26 15:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 8:03 [PATCH next] mm/vmscan: __isolate_lru_page_prepare clean up Alex Shi
2020-11-20 23:13 ` Andrew Morton
2020-11-22 12:00 ` Alex Shi
2020-11-22 12:35 ` Matthew Wilcox
2020-11-22 14:00 ` Alex Shi
2020-11-24 11:21 ` Vlastimil Babka
2020-11-25 23:43 ` Andrew Morton
2020-11-26 2:25 ` Alex Shi
2020-11-26 15:23 ` Vlastimil Babka [this message]
2020-11-27 1:56 ` Alex Shi
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