From: "Huang, Ying" <ying.huang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Huang Ying <ying.huang@intel.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
Shaohua Li <shli@kernel.org>, Hugh Dickins <hughd@google.com>,
Fengguang Wu <fengguang.wu@intel.com>,
Tim Chen <tim.c.chen@intel.com>,
Dave Hansen <dave.hansen@intel.com>
Subject: [PATCH -mm -v4 4/5] mm, swap: Add sysfs interface for VMA based swap readahead
Date: Mon, 7 Aug 2017 13:40:37 +0800 [thread overview]
Message-ID: <20170807054038.1843-5-ying.huang@intel.com> (raw)
In-Reply-To: <20170807054038.1843-1-ying.huang@intel.com>
From: Huang Ying <ying.huang@intel.com>
The sysfs interface to control the VMA based swap readahead is added
as follow,
/sys/kernel/mm/swap/vma_ra_enabled
Enable the VMA based swap readahead algorithm, or use the original
global swap readahead algorithm.
/sys/kernel/mm/swap/vma_ra_max_order
Set the max order of the readahead window size for the VMA based swap
readahead algorithm.
The corresponding ABI documentation is added too.
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
---
Documentation/ABI/testing/sysfs-kernel-mm-swap | 26 +++++++++
mm/swap_state.c | 80 ++++++++++++++++++++++++++
2 files changed, 106 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-kernel-mm-swap
diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-swap b/Documentation/ABI/testing/sysfs-kernel-mm-swap
new file mode 100644
index 000000000000..587db52084c7
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-swap
@@ -0,0 +1,26 @@
+What: /sys/kernel/mm/swap/
+Date: August 2017
+Contact: Linux memory management mailing list <linux-mm@kvack.org>
+Description: Interface for swapping
+
+What: /sys/kernel/mm/swap/vma_ra_enabled
+Date: August 2017
+Contact: Linux memory management mailing list <linux-mm@kvack.org>
+Description: Enable/disable VMA based swap readahead.
+
+ If set to true, the VMA based swap readahead algorithm
+ will be used for swappable anonymous pages mapped in a
+ VMA, and the global swap readahead algorithm will be
+ still used for tmpfs etc. other users. If set to
+ false, the global swap readahead algorithm will be
+ used for all swappable pages.
+
+What: /sys/kernel/mm/swap/vma_ra_max_order
+Date: August 2017
+Contact: Linux memory management mailing list <linux-mm@kvack.org>
+Description: The max readahead size in order for VMA based swap readahead
+
+ VMA based swap readahead algorithm will readahead at
+ most 1 << max_order pages for each readahead. The
+ real readahead size for each readahead will be scaled
+ according to the estimation algorithm.
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 3885fef7bdf5..71ce2d1ccbf7 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -751,3 +751,83 @@ struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
return read_swap_cache_async(fentry, gfp_mask, vma, vmf->address,
swap_ra->win == 1);
}
+
+#ifdef CONFIG_SYSFS
+static ssize_t vma_ra_enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%s\n", swap_vma_readahead ? "true" : "false");
+}
+static ssize_t vma_ra_enabled_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (!strncmp(buf, "true", 4) || !strncmp(buf, "1", 1))
+ swap_vma_readahead = true;
+ else if (!strncmp(buf, "false", 5) || !strncmp(buf, "0", 1))
+ swap_vma_readahead = false;
+ else
+ return -EINVAL;
+
+ return count;
+}
+static struct kobj_attribute vma_ra_enabled_attr =
+ __ATTR(vma_ra_enabled, 0644, vma_ra_enabled_show,
+ vma_ra_enabled_store);
+
+static ssize_t vma_ra_max_order_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", swap_ra_max_order);
+}
+static ssize_t vma_ra_max_order_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err, v;
+
+ err = kstrtoint(buf, 10, &v);
+ if (err || v > SWAP_RA_ORDER_CEILING || v <= 0)
+ return -EINVAL;
+
+ swap_ra_max_order = v;
+
+ return count;
+}
+static struct kobj_attribute vma_ra_max_order_attr =
+ __ATTR(vma_ra_max_order, 0644, vma_ra_max_order_show,
+ vma_ra_max_order_store);
+
+static struct attribute *swap_attrs[] = {
+ &vma_ra_enabled_attr.attr,
+ &vma_ra_max_order_attr.attr,
+ NULL,
+};
+
+static struct attribute_group swap_attr_group = {
+ .attrs = swap_attrs,
+};
+
+static int __init swap_init_sysfs(void)
+{
+ int err;
+ struct kobject *swap_kobj;
+
+ swap_kobj = kobject_create_and_add("swap", mm_kobj);
+ if (!swap_kobj) {
+ pr_err("failed to create swap kobject\n");
+ return -ENOMEM;
+ }
+ err = sysfs_create_group(swap_kobj, &swap_attr_group);
+ if (err) {
+ pr_err("failed to register swap group\n");
+ goto delete_obj;
+ }
+ return 0;
+
+delete_obj:
+ kobject_put(swap_kobj);
+ return err;
+}
+subsys_initcall(swap_init_sysfs);
+#endif
--
2.11.0
next prev parent reply other threads:[~2017-08-07 5:42 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 5:40 [PATCH -mm -v4 0/5] mm, swap: VMA based swap readahead Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 1/5] mm, swap: Add swap readahead hit statistics Huang, Ying
2017-08-09 21:50 ` Andrew Morton
2017-08-09 23:17 ` Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 2/5] mm, swap: Fix swap readahead marking Huang, Ying
2017-08-07 5:40 ` [PATCH -mm -v4 3/5] mm, swap: VMA based swap readahead Huang, Ying
2017-09-13 1:40 ` Minchan Kim
2017-09-13 21:02 ` Andrew Morton
2017-09-14 0:53 ` Huang, Ying
2017-09-14 8:15 ` Minchan Kim
2017-09-14 7:53 ` Minchan Kim
2017-09-14 12:01 ` Huang, Ying
2017-09-14 13:14 ` Minchan Kim
2017-09-14 21:21 ` Andrew Morton
2017-09-15 3:15 ` Huang, Ying
2017-09-15 3:42 ` Minchan Kim
2017-09-15 4:46 ` Huang, Ying
2017-08-07 5:40 ` Huang, Ying [this message]
2017-08-07 5:40 ` [PATCH -mm -v4 5/5] mm, swap: Don't use VMA based swap readahead if HDD is used as swap Huang, Ying
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