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

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Date:   Tue, 19 Jan 2021 09:44:24 -0800
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Miaohe Lin <linmiaohe@...wei.com>,
        Oscar Salvador <osalvador@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     david@...hat.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/hugetlb: avoid unnecessary hugetlb_acct_memory()
 call

On 1/15/21 1:44 AM, Miaohe Lin wrote:
> 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 ?

Thank you and Andrew.

Looks like Andrew updated the commit message and added to his tree.

-- 
Mike Kravetz