From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BFD651D0B91; Wed, 2 Oct 2024 14:50:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880609; cv=none; b=OYoZ6h4PjfGFo20liNHoqwQ/Lhs3TKwI9qvVFpdeR9IwytyputftSw85IcD8H396rgJsMDsmIP63ZyB4q7/7+XcLUxJECH7iv8edWlizraIzxc6eUyc5NHi+RDsTTsJaLps2jLbNZyvowZisoxcNGJjhzqBsrrnYkdmHyuwJSZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880609; c=relaxed/simple; bh=sJJs4iaiaFcblTaunrVZPr4wXdUswj6TgZ9hftNr23w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=EC3hOU2zhWUqmtgOuQ8SCcuANuAFr6PXjvCq2M4lV28W4DtlN/V6ph3SO6fMWc/w4uGJg/mpKmGbsMHldHrOMfHO/7Ey7oLzLqpMuFcr+Lmu7PsYVJhNdT1DGgp96ryg8aigWlO3yeAlTNzzAxMoWJ+4Jtj+GwdngJJP/foRXaw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a/WbjiAn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="a/WbjiAn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B93BC4CECD; Wed, 2 Oct 2024 14:50:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727880609; bh=sJJs4iaiaFcblTaunrVZPr4wXdUswj6TgZ9hftNr23w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a/WbjiAnP8gpktv3sCXQKwUSnVyyuTd3s1X9W85FSVdtR/xjq5K2sCExaXzoMpoXF wPKOLPccMq8uyYPNwEUSoo1tvlyPfEcmiF+JrFSlF87jP0nPC2QbH8vrw48YRnY4/N XM1k/wVWi/RbBQ84UOk4oojbKRx/u050Kvmj5QR8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kairui Song , "Matthew Wilcox (Oracle)" , Andrew Morton Subject: [PATCH 6.6 518/538] mm/filemap: optimize filemap folio adding Date: Wed, 2 Oct 2024 15:02:37 +0200 Message-ID: <20241002125812.894504322@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125751.964700919@linuxfoundation.org> References: <20241002125751.964700919@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kairui Song commit 6758c1128ceb45d1a35298912b974eb4895b7dd9 upstream. Instead of doing multiple tree walks, do one optimism range check with lock hold, and exit if raced with another insertion. If a shadow exists, check it with a new xas_get_order helper before releasing the lock to avoid redundant tree walks for getting its order. Drop the lock and do the allocation only if a split is needed. In the best case, it only need to walk the tree once. If it needs to alloc and split, 3 walks are issued (One for first ranged conflict check and order retrieving, one for the second check after allocation, one for the insert after split). Testing with 4K pages, in an 8G cgroup, with 16G brd as block device: echo 3 > /proc/sys/vm/drop_caches fio -name=cached --numjobs=16 --filename=/mnt/test.img \ --buffered=1 --ioengine=mmap --rw=randread --time_based \ --ramp_time=30s --runtime=5m --group_reporting Before: bw ( MiB/s): min= 1027, max= 3520, per=100.00%, avg=2445.02, stdev=18.90, samples=8691 iops : min=263001, max=901288, avg=625924.36, stdev=4837.28, samples=8691 After (+7.3%): bw ( MiB/s): min= 493, max= 3947, per=100.00%, avg=2625.56, stdev=25.74, samples=8651 iops : min=126454, max=1010681, avg=672142.61, stdev=6590.48, samples=8651 Test result with THP (do a THP randread then switch to 4K page in hope it issues a lot of splitting): echo 3 > /proc/sys/vm/drop_caches fio -name=cached --numjobs=16 --filename=/mnt/test.img \ --buffered=1 --ioengine=mmap -thp=1 --readonly \ --rw=randread --time_based --ramp_time=30s --runtime=10m \ --group_reporting fio -name=cached --numjobs=16 --filename=/mnt/test.img \ --buffered=1 --ioengine=mmap \ --rw=randread --time_based --runtime=5s --group_reporting Before: bw ( KiB/s): min= 4141, max=14202, per=100.00%, avg=7935.51, stdev=96.85, samples=18976 iops : min= 1029, max= 3548, avg=1979.52, stdev=24.23, samples=18976ยท READ: bw=4545B/s (4545B/s), 4545B/s-4545B/s (4545B/s-4545B/s), io=64.0KiB (65.5kB), run=14419-14419msec After (+12.5%): bw ( KiB/s): min= 4611, max=15370, per=100.00%, avg=8928.74, stdev=105.17, samples=19146 iops : min= 1151, max= 3842, avg=2231.27, stdev=26.29, samples=19146 READ: bw=4635B/s (4635B/s), 4635B/s-4635B/s (4635B/s-4635B/s), io=64.0KiB (65.5kB), run=14137-14137msec The performance is better for both 4K (+7.5%) and THP (+12.5%) cached read. Link: https://lkml.kernel.org/r/20240415171857.19244-5-ryncsn@gmail.com Signed-off-by: Kairui Song Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Closes: https://lore.kernel.org/linux-mm/A5A976CB-DB57-4513-A700-656580488AB6@flyingcircus.io/ [ kasong@tencent.com: minor adjustment of variable declarations ] Signed-off-by: Greg Kroah-Hartman --- lib/test_xarray.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ mm/filemap.c | 53 +++++++++++++++++++++++++++++++++++------------- 2 files changed, 98 insertions(+), 14 deletions(-) --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -1789,6 +1789,64 @@ static noinline void check_xas_get_order } } +static noinline void check_xas_conflict_get_order(struct xarray *xa) +{ + XA_STATE(xas, xa, 0); + + void *entry; + int only_once; + unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1; + unsigned int order; + unsigned long i, j, k; + + for (order = 0; order < max_order; order++) { + for (i = 0; i < 10; i++) { + xas_set_order(&xas, i << order, order); + do { + xas_lock(&xas); + xas_store(&xas, xa_mk_value(i)); + xas_unlock(&xas); + } while (xas_nomem(&xas, GFP_KERNEL)); + + /* + * Ensure xas_get_order works with xas_for_each_conflict. + */ + j = i << order; + for (k = 0; k < order; k++) { + only_once = 0; + xas_set_order(&xas, j + (1 << k), k); + xas_lock(&xas); + xas_for_each_conflict(&xas, entry) { + XA_BUG_ON(xa, entry != xa_mk_value(i)); + XA_BUG_ON(xa, xas_get_order(&xas) != order); + only_once++; + } + XA_BUG_ON(xa, only_once != 1); + xas_unlock(&xas); + } + + if (order < max_order - 1) { + only_once = 0; + xas_set_order(&xas, (i & ~1UL) << order, order + 1); + xas_lock(&xas); + xas_for_each_conflict(&xas, entry) { + XA_BUG_ON(xa, entry != xa_mk_value(i)); + XA_BUG_ON(xa, xas_get_order(&xas) != order); + only_once++; + } + XA_BUG_ON(xa, only_once != 1); + xas_unlock(&xas); + } + + xas_set_order(&xas, i << order, order); + xas_lock(&xas); + xas_store(&xas, NULL); + xas_unlock(&xas); + } + } +} + + static noinline void check_destroy(struct xarray *xa) { unsigned long index; @@ -1839,6 +1897,7 @@ static int xarray_checks(void) check_multi_store(&array); check_get_order(&array); check_xas_get_order(&array); + check_xas_conflict_get_order(&array); check_xa_alloc(); check_find(&array); check_find_entry(&array); --- a/mm/filemap.c +++ b/mm/filemap.c @@ -846,6 +846,8 @@ noinline int __filemap_add_folio(struct { XA_STATE(xas, &mapping->i_pages, index); int huge = folio_test_hugetlb(folio); + void *alloced_shadow = NULL; + int alloced_order = 0; bool charged = false; long nr = 1; @@ -868,16 +870,10 @@ noinline int __filemap_add_folio(struct folio->mapping = mapping; folio->index = xas.xa_index; - do { - unsigned int order = xa_get_order(xas.xa, xas.xa_index); + for (;;) { + int order = -1, split_order = 0; void *entry, *old = NULL; - if (order > folio_order(folio)) { - xas_split_alloc(&xas, xa_load(xas.xa, xas.xa_index), - order, gfp); - if (xas_error(&xas)) - goto error; - } xas_lock_irq(&xas); xas_for_each_conflict(&xas, entry) { old = entry; @@ -885,19 +881,33 @@ noinline int __filemap_add_folio(struct xas_set_err(&xas, -EEXIST); goto unlock; } + /* + * If a larger entry exists, + * it will be the first and only entry iterated. + */ + if (order == -1) + order = xas_get_order(&xas); + } + + /* entry may have changed before we re-acquire the lock */ + if (alloced_order && (old != alloced_shadow || order != alloced_order)) { + xas_destroy(&xas); + alloced_order = 0; } if (old) { - if (shadowp) - *shadowp = old; - /* entry may have been split before we acquired lock */ - order = xa_get_order(xas.xa, xas.xa_index); - if (order > folio_order(folio)) { + if (order > 0 && order > folio_order(folio)) { /* How to handle large swap entries? */ BUG_ON(shmem_mapping(mapping)); + if (!alloced_order) { + split_order = order; + goto unlock; + } xas_split(&xas, old, order); xas_reset(&xas); } + if (shadowp) + *shadowp = old; } xas_store(&xas, folio); @@ -913,9 +923,24 @@ noinline int __filemap_add_folio(struct __lruvec_stat_mod_folio(folio, NR_FILE_THPS, nr); } + unlock: xas_unlock_irq(&xas); - } while (xas_nomem(&xas, gfp)); + + /* split needed, alloc here and retry. */ + if (split_order) { + xas_split_alloc(&xas, old, split_order, gfp); + if (xas_error(&xas)) + goto error; + alloced_shadow = old; + alloced_order = split_order; + xas_reset(&xas); + continue; + } + + if (!xas_nomem(&xas, gfp)) + break; + } if (xas_error(&xas)) goto error;