From: SeongJae Park <sjpark@amazon.com> To: <sjpark@amazon.com> Cc: <axboe@kernel.dk>, <konrad.wilk@oracle.com>, <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <pdurrant@amazon.com>, <roger.pau@citrix.com>, <sj38.park@gmail.com>, <xen-devel@lists.xenproject.org>, SeongJae Park <sjpark@amazon.de> Subject: [PATCH v4 1/2] xenbus/backend: Add memory pressure handler callback Date: Mon, 9 Dec 2019 20:43:04 +0100 [thread overview] Message-ID: <20191209194305.20828-2-sjpark@amazon.com> (raw) In-Reply-To: <20191209194305.20828-1-sjpark@amazon.com> From: SeongJae Park <sjpark@amazon.de> Granting pages consumes backend system memory. In systems configured with insufficient spare memory for those pages, it can cause a memory pressure situation. However, finding the optimal amount of the spare memory is challenging for large systems having dynamic resource utilization patterns. Also, such a static configuration might lacks a flexibility. To mitigate such problems, this commit adds a memory reclaim callback to 'xenbus_driver'. Using this facility, 'xenbus' would be able to monitor a memory pressure and request specific domains of specific backend drivers which causing the given pressure to voluntarily release its memory. That said, this commit simply requests every callback registered driver to release its memory for every domain, rather than issueing the requests to the drivers and domain in charge. Such things would be a future work. Also, this commit focuses on memory only. However, it would be ablt to be extended for general resources. Signed-off-by: SeongJae Park <sjpark@amazon.de> --- drivers/xen/xenbus/xenbus_probe_backend.c | 31 +++++++++++++++++++++++ include/xen/xenbus.h | 1 + 2 files changed, 32 insertions(+) diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c index b0bed4faf44c..cd5fd1cd8de3 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -248,6 +248,34 @@ static int backend_probe_and_watch(struct notifier_block *notifier, return NOTIFY_DONE; } +static int xenbus_backend_reclaim(struct device *dev, void *data) +{ + struct xenbus_driver *drv; + if (!dev->driver) + return -ENOENT; + drv = to_xenbus_driver(dev->driver); + if (drv && drv->reclaim) + drv->reclaim(to_xenbus_device(dev), DOMID_INVALID); + return 0; +} + +/* + * Returns 0 always because we are using shrinker to only detect memory + * pressure. + */ +static unsigned long xenbus_backend_shrink_count(struct shrinker *shrinker, + struct shrink_control *sc) +{ + bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, + xenbus_backend_reclaim); + return 0; +} + +static struct shrinker xenbus_backend_shrinker = { + .count_objects = xenbus_backend_shrink_count, + .seeks = DEFAULT_SEEKS, +}; + static int __init xenbus_probe_backend_init(void) { static struct notifier_block xenstore_notifier = { @@ -264,6 +292,9 @@ static int __init xenbus_probe_backend_init(void) register_xenstore_notifier(&xenstore_notifier); + if (register_shrinker(&xenbus_backend_shrinker)) + pr_warn("shrinker registration failed\n"); + return 0; } subsys_initcall(xenbus_probe_backend_init); diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h index 869c816d5f8c..52aaf4f78400 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -104,6 +104,7 @@ struct xenbus_driver { struct device_driver driver; int (*read_otherend_details)(struct xenbus_device *dev); int (*is_ready)(struct xenbus_device *dev); + unsigned (*reclaim)(struct xenbus_device *dev, domid_t domid); }; static inline struct xenbus_driver *to_xenbus_driver(struct device_driver *drv) -- 2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: SeongJae Park <sjpark@amazon.com> To: <sjpark@amazon.com> Cc: axboe@kernel.dk, sj38.park@gmail.com, konrad.wilk@oracle.com, pdurrant@amazon.com, SeongJae Park <sjpark@amazon.de>, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, roger.pau@citrix.com Subject: [Xen-devel] [PATCH v4 1/2] xenbus/backend: Add memory pressure handler callback Date: Mon, 9 Dec 2019 20:43:04 +0100 [thread overview] Message-ID: <20191209194305.20828-2-sjpark@amazon.com> (raw) In-Reply-To: <20191209194305.20828-1-sjpark@amazon.com> From: SeongJae Park <sjpark@amazon.de> Granting pages consumes backend system memory. In systems configured with insufficient spare memory for those pages, it can cause a memory pressure situation. However, finding the optimal amount of the spare memory is challenging for large systems having dynamic resource utilization patterns. Also, such a static configuration might lacks a flexibility. To mitigate such problems, this commit adds a memory reclaim callback to 'xenbus_driver'. Using this facility, 'xenbus' would be able to monitor a memory pressure and request specific domains of specific backend drivers which causing the given pressure to voluntarily release its memory. That said, this commit simply requests every callback registered driver to release its memory for every domain, rather than issueing the requests to the drivers and domain in charge. Such things would be a future work. Also, this commit focuses on memory only. However, it would be ablt to be extended for general resources. Signed-off-by: SeongJae Park <sjpark@amazon.de> --- drivers/xen/xenbus/xenbus_probe_backend.c | 31 +++++++++++++++++++++++ include/xen/xenbus.h | 1 + 2 files changed, 32 insertions(+) diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c index b0bed4faf44c..cd5fd1cd8de3 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -248,6 +248,34 @@ static int backend_probe_and_watch(struct notifier_block *notifier, return NOTIFY_DONE; } +static int xenbus_backend_reclaim(struct device *dev, void *data) +{ + struct xenbus_driver *drv; + if (!dev->driver) + return -ENOENT; + drv = to_xenbus_driver(dev->driver); + if (drv && drv->reclaim) + drv->reclaim(to_xenbus_device(dev), DOMID_INVALID); + return 0; +} + +/* + * Returns 0 always because we are using shrinker to only detect memory + * pressure. + */ +static unsigned long xenbus_backend_shrink_count(struct shrinker *shrinker, + struct shrink_control *sc) +{ + bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, + xenbus_backend_reclaim); + return 0; +} + +static struct shrinker xenbus_backend_shrinker = { + .count_objects = xenbus_backend_shrink_count, + .seeks = DEFAULT_SEEKS, +}; + static int __init xenbus_probe_backend_init(void) { static struct notifier_block xenstore_notifier = { @@ -264,6 +292,9 @@ static int __init xenbus_probe_backend_init(void) register_xenstore_notifier(&xenstore_notifier); + if (register_shrinker(&xenbus_backend_shrinker)) + pr_warn("shrinker registration failed\n"); + return 0; } subsys_initcall(xenbus_probe_backend_init); diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h index 869c816d5f8c..52aaf4f78400 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -104,6 +104,7 @@ struct xenbus_driver { struct device_driver driver; int (*read_otherend_details)(struct xenbus_device *dev); int (*is_ready)(struct xenbus_device *dev); + unsigned (*reclaim)(struct xenbus_device *dev, domid_t domid); }; static inline struct xenbus_driver *to_xenbus_driver(struct device_driver *drv) -- 2.17.1 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-12-09 19:43 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-09 19:43 [PATCH v4 0/2] xenbus/backend: Add a memory pressure handler callback SeongJae Park 2019-12-09 19:43 ` [Xen-devel] " SeongJae Park 2019-12-09 19:43 ` SeongJae Park [this message] 2019-12-09 19:43 ` [Xen-devel] [PATCH v4 1/2] xenbus/backend: Add " SeongJae Park 2019-12-10 6:11 ` Jürgen Groß 2019-12-10 6:11 ` [Xen-devel] " Jürgen Groß 2019-12-10 6:19 ` SeongJae Park 2019-12-10 6:19 ` [Xen-devel] " SeongJae Park 2019-12-10 6:23 ` Jürgen Groß 2019-12-10 6:23 ` [Xen-devel] " Jürgen Groß 2019-12-10 6:29 ` SeongJae Park 2019-12-10 6:29 ` [Xen-devel] " SeongJae Park 2019-12-09 19:43 ` [PATCH v4 2/2] xen/blkback: Squeeze page pools if a memory pressure is detected SeongJae Park 2019-12-09 19:43 ` [Xen-devel] " SeongJae Park 2019-12-10 6:24 ` Jürgen Groß 2019-12-10 6:24 ` [Xen-devel] " Jürgen Groß
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