From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7F469385529; Mon, 18 May 2026 08:07:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.2 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779091649; cv=none; b=bkr4UPRvon7KXCzTgEaDAfEHPd+YQny6vJWofqF2AAdzbuzmKl/wg9QEXNXhnIjQDxl7k0EUlr0b32fUyvJeFBM8yCmTuN951Bx+RcsUVsKJBifHQ2899ZCsritBnc6Xs5ANl52yMpPwqVTfTXmorlL6LKL/6QysWa66UREmkZo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779091649; c=relaxed/simple; bh=WgKaypdyj0SyYNh1yfbEr55XfGaIgfSFSyRO86SJIRA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XOX0+Egooqqq72IwDcWOpnZig40lpbjZccCd1uwlN2vPSYhxjhQZRYYj8ayd3QYh15lxD3y8Hu2AaaNcjoX3kPCd5TCPYw2OYlbrWoMciPC8QZ/m8Wv+6EO7bx961mT1joXQ6wNM/PidkdQZ6K7Os0HjPgmbFkL/Tqa6Vc/oAZg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=WKZ0s76Y; arc=none smtp.client-ip=117.135.210.2 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="WKZ0s76Y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Message-ID:Date:MIME-Version:Subject:To:From: Content-Type; bh=kj1XPRaTLuqwRm8giTJqySkcps/Wa5KEg3Ludru1PNg=; b=WKZ0s76YiThuF/hvOpmpjjm8EJKli1U78Pqh9FLwfJbRL0b6HYpniryi7dd8Eo 5s7bxF1C+jEIjC/u/x/vJtZXeDDWMDr/6MRoSr9ddoeyGzL7tZF8UIbBa2X/M1ON /TUqF8fm87wLyGAHm3W9EQ41mFPGuttXANdKvqvh1QdR4= Received: from [10.42.20.201] (unknown []) by gzga-smtp-mtada-g0-1 (Coremail) with SMTP id _____wDHV5NayApq2nD5Bw--.51111S2; Mon, 18 May 2026 16:05:48 +0800 (CST) Message-ID: <885033da-b1a1-4cc3-b2a1-0bc786c77b76@163.com> Date: Mon, 18 May 2026 16:05:46 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 3/4] mm/shmem: optimize file read with folio batching To: Baolin Wang , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hugh Dickins , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , "Matthew Wilcox (Oracle)" , Jan Kara , Chi Zhiling References: <20260515094702.1092355-1-chizhiling@163.com> <20260515094702.1092355-4-chizhiling@163.com> Content-Language: en-US From: Chi Zhiling In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wDHV5NayApq2nD5Bw--.51111S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7uryrAF48AFyDWw47GF1ftFb_yoW8uryUpF Z5GanxJF4DJr17Crsaqw4xZFyYg34kXa1YyFWxJ3W7AFn0yFn5KFyxK3W5GFyrA348Z3WI vF1jq3sFg3WDt3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UtPEhUUUUU= X-CM-SenderInfo: hfkl6xxlol0wi6rwjhhfrp/xtbC2xxmBGoKyFwJeQAA3h On 5/18/26 14:57, Baolin Wang wrote: > On 5/15/26 5:47 PM, Chi Zhiling wrote: >> From: Chi Zhiling >> >> Optimize shmem file read by implementing folio batching in the read >> iteration path. Only uptodate folios are added to the batch, ensuring >> all folios in the batch are valid and ready for use without additional >> checking. >> >> Signed-off-by: Chi Zhiling >> --- >>   mm/shmem.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++----- >>   1 file changed, 93 insertions(+), 9 deletions(-) >> >> diff --git a/mm/shmem.c b/mm/shmem.c >> index 767610f78d0d..4bc4e463ca97 100644 >> --- a/mm/shmem.c >> +++ b/mm/shmem.c >> @@ -3348,16 +3348,100 @@ shmem_write_end(const struct kiocb *iocb, >> struct address_space *mapping, >>       return copied; >>   } >> +static pgoff_t shmem_get_read_batch(struct address_space *mapping, >> +        pgoff_t index, pgoff_t max, struct folio_batch *fbatch) >> +{ >> +    XA_STATE(xas, &mapping->i_pages, index); >> +    struct folio *folio; >> +    pgoff_t end = max; >> + >> +    rcu_read_lock(); >> +    xas_for_each(&xas, folio, max) { >> +        if (xas_retry(&xas, folio)) >> +            continue; >> +        if (xa_is_value(folio)) { >> +            end = xas.xa_index; >> +            break; >> +        } >> +        if (!folio_try_get(folio)) >> +            goto retry; >> + >> +        if (unlikely(folio != xas_reload(&xas))) >> +            goto put_folio; >> + >> +        end = folio_next_index(folio); >> + >> +        if (!folio_test_uptodate(folio)) { >> +            xas_advance(&xas, end - 1); >> +            folio_put(folio); >> +            continue; >> +        } >> +        if (!folio_batch_add(fbatch, folio)) >> +            break; >> +        xas_advance(&xas, end - 1); >> +        continue; >> +put_folio: >> +        folio_put(folio); >> +retry: >> +        xas_reset(&xas); >> +    } >> +    rcu_read_unlock(); >> + >> +    return end; >> +} > > I haven't looked at this patch in detail yet, but I feel this part > should belong in mm/filemap.c, or perhaps mm/filemap.c already has a > similar function implemented? Let's wait for Matthew's comments on this. Yes, it's better to put it in filemap.c, but seems no other caller except shmem. :) Thanks,