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Fri, 26 Jul 2024 14:00:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pankajraghav.com; s=MBO0001; t=1721995219; 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=+r0q1aMOVXTo8fjQ8nnAWfzQgFhULOwQhra2cgoZxE8=; b=vn9UpSWjQnJToJQ7MgvGmCbdIjddckWODqQGbZPTylDwxHKMk9MXVR61Qq5VmVG3p+P7aD p7sCN8oJRuQhZSxuwZFxkDZf+SEJPSwBdWveJYsJl602XwnFTf0+gItBPXTnzTKIyYVQuk 31EoyZ69rRBYcJQVnJE5diO8vYbHHfVSkPbwkVfqWNcNedBQZJTREruAhGuiDKCtU2qiOa pqym1ALogrgFsCO+IwniBBWTXPnS6K8nx33ZJH6nsPiSxnji4BtimUWwke01ulb3ezIwx3 Ag2VS/vF7dWywBDZrBykQiDqLYIiA/L/TEOdven9iu8VKXa+3k95y0UlNqApWA== 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: yang@os.amperecomputing.com, linux-kernel@vger.kernel.org, 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, ryan.roberts@arm.com, hch@lst.de, Zi Yan Subject: [PATCH v11 03/10] readahead: allocate folios with mapping_min_order in readahead Date: Fri, 26 Jul 2024 13:59:49 +0200 Message-ID: <20240726115956.643538-4-kernel@pankajraghav.com> In-Reply-To: <20240726115956.643538-1-kernel@pankajraghav.com> References: <20240726115956.643538-1-kernel@pankajraghav.com> MIME-Version: 1.0 X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 9BFB540007 X-Stat-Signature: 1s4149811495j8cei3iir6k3iexpmtqr X-Rspam-User: X-HE-Tag: 1721995222-247745 X-HE-Meta: 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 pczXwYfy acjuX4/qgp1nCmz9jBIVvjTiEPGappiRoVVR3fe0ZXkJNPuOw6YJkLkGEHTMNbaNO8Lc93DL3/SqiSt0V1DvJaEFqQiMkTpHcn9+jUE6ycCxd2GoqNi9NtAH0F2OlhJU7uDltqYHtCNMEOcO0IKz9hUUtMN4sUH8wq3ssrbG+tyFrzYGi+QhbOJxfmIIkJlQpGZIMpUOCwGONrLJWp9iknz8YcqdeZK9g6uqXfZqojnaG1mQpo/inHfMoMQgefmXEWktzrIeam/tPlpXF1rIscPMu8aYtYA8NBrA3Hc7Sf/kYHUIwI/rkNaUH1PkWdIsMJJAwQgv3sCe0AOP1YyoTHeYbxqAM9XZT00Iu 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. 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 | 79 ++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 61 insertions(+), 18 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 3e5239e9e1777..2078c42777a62 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 +224,24 @@ 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; + 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 +255,13 @@ 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 +271,15 @@ 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; } /* @@ -438,13 +455,19 @@ void page_cache_ra_order(struct readahead_control *ractl, struct address_space *mapping = ractl->mapping; pgoff_t start = readahead_index(ractl); pgoff_t index = start; + 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); @@ -454,10 +477,19 @@ void page_cache_ra_order(struct readahead_control *ractl, 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; @@ -465,7 +497,7 @@ 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) @@ -703,8 +735,15 @@ 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) { @@ -714,9 +753,11 @@ 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; @@ -726,7 +767,7 @@ 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; } @@ -741,9 +782,11 @@ 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; @@ -753,10 +796,10 @@ 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; } } }