From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) (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 58A6E39478D; Mon, 18 May 2026 06:57:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.111 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779087451; cv=none; b=cep5FODUGuj7jHlv3AyIfNphX82NbeTYSgjF7e0nOZXQXztEY1qWvR4glM/2B+t5Wu488hxiP34Kw7K6uxneUn0SPg9cNfjF7DvQ2rauaeJwExmpA/iH7+vGTuDRVIk0dOH9aiV6u1o7jZeoT8jAHWhZuoIwLgjd1za7b9TnvnU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779087451; c=relaxed/simple; bh=yhmc/9L78EzB23EhuXeL3kY9eVKiwEFprCswF4mDthg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=d53JCYTDjS9VXTp8uZyV182prVFE/rYQDRxkFBE70yhJEIEW68+tF/8Uy5qdxLWe3ZpxYaR7EDAV9+KngA7pjKZFE121ZOcmQavdJI5RkNbz9W9f+q20IMByOaaVTyZTgkbqNWNXziLG6MGvTwXWgTmhv/iwQF7ySPjPAWHqa3U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=bwDefZI+; arc=none smtp.client-ip=115.124.30.111 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="bwDefZI+" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1779087446; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=4S2UP+4Ec7pYdgX+oP9rm4DXMaK33zfVzNRRNCKcGSc=; b=bwDefZI+zKj3TcwKZ8aJAEfCY9i4WmHW1BmxnBQZ9PzziUM0gSBpOIOl/hOd2fydaZFrYfQeQLHqQuaoHIfByaS3QkI7HPMPCbEtTpG2qW1owFs/d64VYCo34btfQyY0Z0gGUyRu4xMCiuvBhJhg7E6Jji7SoBUr4nE3zukVNkA= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R901e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam011083073210;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---0X34bSjL_1779087443; Received: from 30.74.144.119(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X34bSjL_1779087443 cluster:ay36) by smtp.aliyun-inc.com; Mon, 18 May 2026 14:57:23 +0800 Message-ID: Date: Mon, 18 May 2026 14:57:22 +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: Chi Zhiling , 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> From: Baolin Wang In-Reply-To: <20260515094702.1092355-4-chizhiling@163.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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.