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b=pQzPjEFPD8N74U1fP1gOFDJDMKcIZviYG5+wt0HlBqPGc0RIFUQQW6xd4cnrlyWMq P+Mddndf3V5rcRbC1NkvnFKPsD5HVrspRuDuRkMuJ9YYxbmFpBdRpD5cOfet1H0e+F vD4Ikj+8E/yma5BlgCY/ipAKL46xBGTnuFDdnTI0H1jem5Y1DOlRFu4MWybtgZbb8G +mxx1ZViFrEiDfRwRcCTUIjWRvSOEfqBF9wlB+fLW9LQyTJBphmKyGONFOc72r6nQq kaOwqWlPK8LxWDOTkff6xuvGUAO0mEnPQAibAZRi8BipuaVQ5TAHTH1A9qX7jqJVJ9 424U5byWd05LQ== Date: Wed, 3 Dec 2025 23:25:25 +0000 From: Jaegeuk Kim To: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, Matthew Wilcox Subject: Re: [PATCH 3/3 v2] mm/readahead: try to allocate high order pages for FADVISE_FAV_WILLNEED Message-ID: References: <20251202013212.964298-1-jaegeuk@kernel.org> <20251202013212.964298-4-jaegeuk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251202013212.964298-4-jaegeuk@kernel.org> X-Rspamd-Queue-Id: 8A9A5A0003 X-Rspamd-Server: rspam06 X-Rspam-User: X-Stat-Signature: 7i71orzee3g31zbhptyb1gjxw54kustx X-HE-Tag: 1764804328-907552 X-HE-Meta: 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 q/7rr7cZ Q0uPqK11CyE4R7WRDf5wHuXUbTUOgJZD8rG6DBONvzaQLvBUeYY1mMCXq/Pcuif8uGgqLOkQRBQNH89wE0JPFQgCbSoQQzytV1ay1jSWQjWGGcCfaH8jec/mfhaUYwaeg2w5uC/YJ8J3g6Gj4NElg9RDd6778vgaBwu0gPdjHMTjtaTcakV5DeoxJaNmjoDIs99OCwl6guEnNOGpGEdA45IawnZ+3cuiSgXU9ozylIvHDQJz2lToKnlIQi8pauX5Mya2NGEU8zvVejYx8r2pXbUcjUkPmDxxygjBSV4MiAdoxVBPc1qmclZdANGeCryQn9BXz0hZ/Op02dGG1TkiU7d9kr8xU4iYKp6W0JEVboVLET0MdD6LhATNnpCeHdv54haDZiCX+Oth7EY3NPeSHtkMvvoW33tp0C+4JVlQNmzk03pjAbHExSTRUmQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This patch assigns the max folio order for readahead. After applying this patch, it starts with high-order page allocation successfully as shown in the below traces. Before: f2fs_fadvise: dev = (252,16), ino = 14, i_size = 4294967296 offset:0, len:536870912, advise:3 page_cache_sync_ra: dev=252:16 ino=e index=0 req_count=2048 order=0 size=0 async_size=0 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=0 order=0 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=2048 req_count=2048 order=0 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_unbounded: dev=252:16 ino=e index=2048 nr_to_read=2048 lookahead_size=0 page_cache_sync_ra: dev=252:16 ino=e index=4096 req_count=2048 order=0 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_unbounded: dev=252:16 ino=e index=4096 nr_to_read=2048 lookahead_size=0 page_cache_sync_ra: dev=252:16 ino=e index=6144 req_count=2048 order=0 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_unbounded: dev=252:16 ino=e index=6144 nr_to_read=2048 lookahead_size=0 ... page_cache_sync_ra: dev=252:16 ino=e index=129024 req_count=2048 order=0 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_unbounded: dev=252:16 ino=e index=129024 nr_to_read=2048 lookahead_size=0 After: f2fs_fadvise: dev = (252,16), ino = 14, i_size = 4294967296 offset:0, len:536870912, advise:3 page_cache_sync_ra: dev=252:16 ino=e index=0 req_count=2048 order=0 size=0 async_size=0 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=0 order=2 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=2048 req_count=2048 order=2 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=2048 order=4 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=4096 req_count=2048 order=4 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=4096 order=6 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=6144 req_count=2048 order=6 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=6144 order=8 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=8192 req_count=2048 order=8 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=8192 order=10 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=10240 req_count=2048 order=9 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=10240 order=11 size=2048 async_size=1024 ra_pages=2048 ... page_cache_ra_order: dev=252:16 ino=e index=126976 order=11 size=2048 async_size=1024 ra_pages=2048 page_cache_sync_ra: dev=252:16 ino=e index=129024 req_count=2048 order=9 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=129024 order=11 size=2048 async_size=1024 ra_pages=2048 page_cache_async_ra: dev=252:16 ino=e index=1024 req_count=2048 order=9 size=2048 async_size=1024 ra_pages=2048 mmap_miss=0 prev_pos=-1 For comparion, this is the trace of madvise(MADV_POPULATE_READ) which bumps up the order by 2. page_cache_ra_order: dev=252:16 ino=e index=0 order=0 size=2048 async_size=512 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 0, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: MAJOR|RETRY page_cache_async_ra: dev=252:16 ino=e index=1536 req_count=2048 order=0 size=2048 async_size=512 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=2048 order=2 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 1536, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=2048 req_count=2048 order=2 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=4096 order=4 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 2048, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=4096 req_count=2048 order=4 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=6144 order=6 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 4096, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=6144 req_count=2048 order=6 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=8192 order=8 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 6144, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=8192 req_count=2048 order=8 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=10240 order=10 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 8192, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=10240 req_count=2048 order=9 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 ... f2fs_filemap_fault: dev = (252,16), ino = 14, index = 518144, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=520192 req_count=2048 order=9 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=522240 order=11 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 520192, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY page_cache_async_ra: dev=252:16 ino=e index=522240 req_count=2048 order=9 size=2048 async_size=2048 ra_pages=2048 mmap_miss=0 prev_pos=-1 page_cache_ra_order: dev=252:16 ino=e index=524288 order=11 size=2048 async_size=2048 ra_pages=2048 f2fs_filemap_fault: dev = (252,16), ino = 14, index = 522240, flags: WRITE|KILLABLE|USER|REMOTE|0x8082000, ret: RETRY Cc: linux-mm@kvack.org Cc: Matthew Wilcox (Oracle) Signed-off-by: Jaegeuk Kim --- Change log from v1: - take the same madvise() behavior which bumps up ra->order by 2. mm/readahead.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 54c78f8276fe..61a469117209 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -593,7 +593,8 @@ void page_cache_sync_ra(struct readahead_control *ractl, * trivial case: (index - prev_index) == 1 * unaligned reads: (index - prev_index) == 0 */ - if (!index || req_count > max_pages || index - prev_index <= 1UL) { + if (!index || req_count > max_pages || index - prev_index <= 1UL || + mapping_large_folio_support(ractl->mapping)) { ra->start = index; ra->size = get_init_ra_size(req_count, max_pages); ra->async_size = ra->size > req_count ? ra->size - req_count : @@ -627,7 +628,7 @@ void page_cache_sync_ra(struct readahead_control *ractl, ra->size = min(contig_count + req_count, max_pages); ra->async_size = 1; readit: - ra->order = 0; + ra->order += 2; ractl->_index = ra->start; page_cache_ra_order(ractl, ra); } -- 2.52.0.223.gf5cc29aaa4-goog