From: Roger Pau Monne <roger.pau@citrix.com>
To: <linux-kernel@vger.kernel.org>
Cc: "Roger Pau Monne" <roger.pau@citrix.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Jens Axboe" <axboe@kernel.dk>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"SeongJae Park" <sjpark@amazon.de>,
xen-devel@lists.xenproject.org, linux-block@vger.kernel.org,
"J . Roeleveld" <joost@antarean.org>,
"Jürgen Groß" <jgross@suse.com>
Subject: [PATCH 2/2] xen/blkback: turn the cache purge percent into a parameter
Date: Thu, 15 Oct 2020 16:24:16 +0200 [thread overview]
Message-ID: <20201015142416.70294-3-roger.pau@citrix.com> (raw)
In-Reply-To: <20201015142416.70294-1-roger.pau@citrix.com>
Assume that reads and writes to the variable will be atomic. The worse
that could happen is that one of the purges removes a partially
written percentage of grants, but the cache itself will recover.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: xen-devel@lists.xenproject.org
Cc: linux-block@vger.kernel.org
Cc: J. Roeleveld <joost@antarean.org>
Cc: Jürgen Groß <jgross@suse.com>
---
Documentation/ABI/testing/sysfs-driver-xen-blkback | 9 +++++++++
drivers/block/xen-blkback/blkback.c | 7 +++++--
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-driver-xen-blkback b/Documentation/ABI/testing/sysfs-driver-xen-blkback
index 776f25d335ca..7de791ad61f9 100644
--- a/Documentation/ABI/testing/sysfs-driver-xen-blkback
+++ b/Documentation/ABI/testing/sysfs-driver-xen-blkback
@@ -45,3 +45,12 @@ Description:
to be executed periodically. This parameter controls the time
interval between consecutive executions of the purge mechanism
is set in ms.
+
+What: /sys/module/xen_blkback/parameters/lru_percent_clean
+Date: October 2020
+KernelVersion: 5.10
+Contact: Roger Pau Monné <roger.pau@citrix.com>
+Description:
+ When the persistent grants list is full we will remove unused
+ grants from the list. The percent number of grants to be
+ removed at each LRU execution.
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 6ad9b76fdb2b..772852d45a5a 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -127,7 +127,10 @@ MODULE_PARM_DESC(lru_internval,
* from the list. The percent number of grants to be removed at each LRU
* execution.
*/
-#define LRU_PERCENT_CLEAN 5
+static unsigned int lru_percent_clean = 5;
+module_param_named(lru_percent_clean, lru_percent_clean, uint, 0644);
+MODULE_PARM_DESC(lru_percent_clean,
+ "Percentage of persistent grants to remove from the cache when full");
/* Run-time switchable: /sys/module/blkback/parameters/ */
static unsigned int log_stats;
@@ -404,7 +407,7 @@ static void purge_persistent_gnt(struct xen_blkif_ring *ring)
!ring->blkif->vbd.overflow_max_grants)) {
num_clean = 0;
} else {
- num_clean = (max_pgrants / 100) * LRU_PERCENT_CLEAN;
+ num_clean = (max_pgrants / 100) * lru_percent_clean;
num_clean = ring->persistent_gnt_c - max_pgrants + num_clean;
num_clean = min(ring->persistent_gnt_c, num_clean);
pr_debug("Going to purge at least %u persistent grants\n",
--
2.28.0
next prev parent reply other threads:[~2020-10-15 14:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 14:24 [PATCH 0/2] xen/blkback: add LRU purge parameters Roger Pau Monne
2020-10-15 14:24 ` [PATCH 1/2] xen/blkback: turn the cache purge LRU interval into a parameter Roger Pau Monne
2020-10-15 14:30 ` Jürgen Groß
2020-10-15 15:08 ` SeongJae Park
2020-10-15 14:24 ` Roger Pau Monne [this message]
2020-10-15 14:37 ` [PATCH 2/2] xen/blkback: turn the cache purge percent " Jürgen Groß
2020-10-15 14:44 ` Roger Pau Monné
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