linux-kernel - Re: [PATCH 8/9] mm/madvise: batch tlb flushes for [process_]madvise(MADV_{DONTNEED[

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Message-Id: <20250401211709.81552-1-sj@kernel.org>
Date: Tue,  1 Apr 2025 14:17:09 -0700
From: SeongJae Park <sj@...nel.org>
To: SeongJae Park <sj@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R. Howlett" <howlett@...il.com>,
	David Hildenbrand <david@...hat.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Vlastimil Babka <vbabka@...e.cz>,
	kernel-team@...a.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 8/9] mm/madvise: batch tlb flushes for [process_]madvise(MADV_{DONTNEED[_LOCKED],FREE})

On Mon, 10 Mar 2025 10:23:17 -0700 SeongJae Park <sj@...nel.org> wrote:

> MADV_DONTNEED[_LOCKED] and MADV_FREE internal logics for
> [process_]madvise() can be invoked with batched tlb flushes.  Update
> vector_madvise() and do_madvise(), which are called for the two system
> calls  respectively, to use those in the efficient way.  Initialize an
> mmu_gather object before starting the internal works, and flush the
> gathered tlb entries at once after all the internal works are done.
> 
> Signed-off-by: SeongJae Park <sj@...nel.org>
> ---
>  mm/madvise.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 47 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/madvise.c b/mm/madvise.c
> index d7ea71c6422c..d5f4ce3041a4 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
[...]
> @@ -1639,6 +1642,32 @@ static void madvise_unlock(struct mm_struct *mm, int behavior)
>  		mmap_read_unlock(mm);
>  }
>  
> +static bool madvise_batch_tlb_flush(int behavior)
> +{
> +	switch (behavior) {
> +	case MADV_DONTNEED:
> +	case MADV_DONTNEED_LOCKED:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}

The above function should return true for MADV_FREE, too.  I will make so in the
next spin.


Thanks,
SJ

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