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

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Message-ID: <20210115092849.GC4092@linux>
Date:   Fri, 15 Jan 2021 10:28:49 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, 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

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:

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


-- 
Oscar Salvador
SUSE L3