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Tue, 25 Jun 2024 13:44:37 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1719315877; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ywavaK8QMna1JetTs9rLR1bZJ1v7KeKc0aD3TnIhzwU=; b=ywgdt+Jm+LhNQyXY/UlD36z0PVt6R+zz6kAxj8bDajZJVNOkixhGveWz0fUaBO3Ek8dJ4c GZFkijp/Sn1IDWzOo/69WNGpPYelXmtZsa3tKnRg2e/DzElhZBHCruqtdIt743ANy760ud XDRxMHsnX7Ab1kC4IyQbO8b3UoP/nc4pC9b1Yxq50aQ/ag17Z86wW4tadOz9SDYMQOzyfP 4CV7/xytQv6yyzJVHQFA8x5O5fiybauKLpkWUXQqO+9hBTq3Q4gRm6yJhAVmT3ibGmgP2u OeNEV9/6ooee1VIsbEeQXS428ISzF3cqvZfsAUStPya/+LMYxh2TuX44bTkusw== From: "Pankaj Raghav (Samsung)" To: david@fromorbit.com, willy@infradead.org, chandan.babu@oracle.com, djwong@kernel.org, brauner@kernel.org, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, yang@os.amperecomputing.com, linux-mm@kvack.org, john.g.garry@oracle.com, linux-fsdevel@vger.kernel.org, hare@suse.de, p.raghav@samsung.com, mcgrof@kernel.org, gost.dev@samsung.com, cl@os.amperecomputing.com, linux-xfs@vger.kernel.org, kernel@pankajraghav.com, hch@lst.de, Zi Yan Subject: [PATCH v8 03/10] readahead: allocate folios with mapping_min_order in readahead Date: Tue, 25 Jun 2024 11:44:13 +0000 Message-ID: <20240625114420.719014-4-kernel@pankajraghav.com> In-Reply-To: <20240625114420.719014-1-kernel@pankajraghav.com> References: <20240625114420.719014-1-kernel@pankajraghav.com> MIME-Version: 1.0 X-Stat-Signature: a779b36mjppnokpc1uep9xusebtqdm3t X-Rspamd-Queue-Id: 05E7416001F X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1719315880-534961 X-HE-Meta: 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 30L5lc5e q0VAIN9jOxkvdX+qVbD1HgTgJ8E2SZvZinxAHuBxEAGbOJcm8Enk6EAKGM+xznkRsdV0+EtsfaaNQJbygLfRbwQ8anLJYVHkRIYwlI0xW7u/GJbUFNUNuKiLHdRWWBqwePniRAeFfFrSR4N8oD7903ntP6NQTS4srJsaYKmMPfosFmTwUEK7CWQw1tHMfXUCSlAWPQX0AZ1kC8CuaAW+FEJpARYibk/R7Zv51XsDYgtIG+ew9wSAsK4L/paTESP2LlQr2vsDNQA25QKcOAf8vXQ+++sGNOmu6d+iBE00KxPda1FCc/Aeg4z5Y6g== 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: From: Pankaj Raghav page_cache_ra_unbounded() was allocating single pages (0 order folios) if there was no folio found in an index. Allocate mapping_min_order folios as we need to guarantee the minimum order if it is set. While we are at it, rework the loop in page_cache_ra_unbounded() to advance with the number of pages in a folio instead of just one page at a time. page_cache_ra_order() tries to allocate folio to the page cache with a higher order if the index aligns with that order. Modify it so that the order does not go below the mapping_min_order requirement of the page cache. This function will do the right thing even if the new_order passed is less than the mapping_min_order. When adding new folios to the page cache we must also ensure the index used is aligned to the mapping_min_order as the page cache requires the index to be aligned to the order of the folio. readahead_expand() is called from readahead aops to extend the range of the readahead so this function can assume ractl->_index to be aligned with min_order. Signed-off-by: Pankaj Raghav Co-developed-by: Hannes Reinecke Signed-off-by: Hannes Reinecke Acked-by: Darrick J. Wong --- mm/readahead.c | 81 +++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 63 insertions(+), 18 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 66058ae02f2e..2acfd6447d7b 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -206,9 +206,10 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, unsigned long nr_to_read, unsigned long lookahead_size) { struct address_space *mapping = ractl->mapping; - unsigned long index = readahead_index(ractl); + unsigned long ra_folio_index, index = readahead_index(ractl); gfp_t gfp_mask = readahead_gfp_mask(mapping); - unsigned long i; + unsigned long mark, i = 0; + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); /* * Partway through the readahead operation, we will have added @@ -223,10 +224,26 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, unsigned int nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); + index = mapping_align_index(mapping, index); + + /* + * As iterator `i` is aligned to min_nrpages, round_up the + * difference between nr_to_read and lookahead_size to mark the + * index that only has lookahead or "async_region" to set the + * readahead flag. + */ + ra_folio_index = round_up(readahead_index(ractl) + nr_to_read - lookahead_size, + min_nrpages); + mark = ra_folio_index - index; + if (index != readahead_index(ractl)) { + nr_to_read += readahead_index(ractl) - index; + ractl->_index = index; + } + /* * Preallocate as many pages as we will need. */ - for (i = 0; i < nr_to_read; i++) { + while (i < nr_to_read) { struct folio *folio = xa_load(&mapping->i_pages, index + i); int ret; @@ -240,12 +257,13 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, * not worth getting one just for that. */ read_pages(ractl); - ractl->_index++; - i = ractl->_index + ractl->_nr_pages - index - 1; + ractl->_index += min_nrpages; + i = ractl->_index + ractl->_nr_pages - index; continue; } - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, + mapping_min_folio_order(mapping)); if (!folio) break; @@ -255,14 +273,15 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, if (ret == -ENOMEM) break; read_pages(ractl); - ractl->_index++; - i = ractl->_index + ractl->_nr_pages - index - 1; + ractl->_index += min_nrpages; + i = ractl->_index + ractl->_nr_pages - index; continue; } - if (i == nr_to_read - lookahead_size) + if (i == mark) folio_set_readahead(folio); ractl->_workingset |= folio_test_workingset(folio); - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; + i += min_nrpages; } /* @@ -492,13 +511,19 @@ void page_cache_ra_order(struct readahead_control *ractl, { struct address_space *mapping = ractl->mapping; pgoff_t index = readahead_index(ractl); + unsigned int min_order = mapping_min_folio_order(mapping); pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; pgoff_t mark = index + ra->size - ra->async_size; unsigned int nofs; int err = 0; gfp_t gfp = readahead_gfp_mask(mapping); + unsigned int min_ra_size = max(4, mapping_min_folio_nrpages(mapping)); - if (!mapping_large_folio_support(mapping) || ra->size < 4) + /* + * Fallback when size < min_nrpages as each folio should be + * at least min_nrpages anyway. + */ + if (!mapping_large_folio_support(mapping) || ra->size < min_ra_size) goto fallback; limit = min(limit, index + ra->size - 1); @@ -507,11 +532,20 @@ void page_cache_ra_order(struct readahead_control *ractl, new_order += 2; new_order = min(mapping_max_folio_order(mapping), new_order); new_order = min_t(unsigned int, new_order, ilog2(ra->size)); + new_order = max(new_order, min_order); } /* See comment in page_cache_ra_unbounded() */ nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); + /* + * If the new_order is greater than min_order and index is + * already aligned to new_order, then this will be noop as index + * aligned to new_order should also be aligned to min_order. + */ + ractl->_index = mapping_align_index(mapping, index); + index = readahead_index(ractl); + while (index <= limit) { unsigned int order = new_order; @@ -519,7 +553,7 @@ void page_cache_ra_order(struct readahead_control *ractl, if (index & ((1UL << order) - 1)) order = __ffs(index); /* Don't allocate pages past EOF */ - while (index + (1UL << order) - 1 > limit) + while (order > min_order && index + (1UL << order) - 1 > limit) order--; err = ra_alloc_folio(ractl, index, mark, order, gfp); if (err) @@ -783,8 +817,15 @@ void readahead_expand(struct readahead_control *ractl, struct file_ra_state *ra = ractl->ra; pgoff_t new_index, new_nr_pages; gfp_t gfp_mask = readahead_gfp_mask(mapping); + unsigned long min_nrpages = mapping_min_folio_nrpages(mapping); + unsigned int min_order = mapping_min_folio_order(mapping); new_index = new_start / PAGE_SIZE; + /* + * Readahead code should have aligned the ractl->_index to + * min_nrpages before calling readahead aops. + */ + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); /* Expand the leading edge downwards */ while (ractl->_index > new_index) { @@ -794,9 +835,11 @@ void readahead_expand(struct readahead_control *ractl, if (folio && !xa_is_value(folio)) return; /* Folio apparently present */ - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, min_order); if (!folio) return; + + index = mapping_align_index(mapping, index); if (filemap_add_folio(mapping, folio, index, gfp_mask) < 0) { folio_put(folio); return; @@ -806,7 +849,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; ractl->_index = folio->index; } @@ -821,9 +864,11 @@ void readahead_expand(struct readahead_control *ractl, if (folio && !xa_is_value(folio)) return; /* Folio apparently present */ - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, min_order); if (!folio) return; + + index = mapping_align_index(mapping, index); if (filemap_add_folio(mapping, folio, index, gfp_mask) < 0) { folio_put(folio); return; @@ -833,10 +878,10 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; if (ra) { - ra->size++; - ra->async_size++; + ra->size += min_nrpages; + ra->async_size += min_nrpages; } } }