linux-kernel - Re: [PATCH v2] mm/hugetlb: avoid unnecessary hugetlb_acct

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Date:   Fri, 15 Jan 2021 17:44:08 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Oscar Salvador <osalvador@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     <mike.kravetz@...cle.com>, <david@...hat.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mm/hugetlb: avoid unnecessary hugetlb_acct_memory()
 call

Hi:

On 2021/1/15 17:28, Oscar Salvador wrote:
> On Fri, Jan 15, 2021 at 04:20:13AM -0500, Miaohe Lin wrote:
>> When gbl_reserve is 0, hugetlb_acct_memory() will do nothing except holding
>> and releasing hugetlb_lock. We should avoid this unnecessary hugetlb_lock
>> lock/unlock cycle which is happening on 'most' hugetlb munmap operations by
>> check delta against 0 at the beginning of hugetlb_acct_memory.
>>
>> Reviewed-by: David Hildenbrand <david@...hat.com>
>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> 
> I would avoid mentioning gbl_reserve as not all callers use it, and focus
> on what delta means:
> 
> "When reservation accounting remains unchanged..", but anyway:

Sounds good. Maybe Andrew could kindly do this if this patch is picked up ?

> 
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> 
> 

Many thanks for your review.