* [PATCH v2 0/3] xen: optimize xenbus performance
@ 2017-01-16 14:15 Juergen Gross
2017-01-16 14:15 ` [PATCH v2 2/3] xen: modify xenstore watch event interface Juergen Gross
0 siblings, 1 reply; 2+ messages in thread
From: Juergen Gross @ 2017-01-16 14:15 UTC (permalink / raw)
To: linux-kernel, xen-devel
Cc: boris.ostrovsky, Juergen Gross, konrad.wilk, roger.pau, wei.liu2,
paul.durrant, netdev
The xenbus driver used for communication with Xenstore (all kernel
accesses to Xenstore and in case of Xenstore living in another domain
all accesses of the local domain to Xenstore) is rather simple
especially regarding multiple concurrent accesses: they are just being
serialized in spite of Xenstore being capable to handle multiple
parallel accesses.
Clean up the external interface(s) of xenbus and optimize its
performance by allowing multiple concurrent accesses to Xenstore.
V2:
- patch 1: update commit message, re-add lost copyright
- patch 3: address comments of Boris Ostrovsky:
- guard xs_request_id by lock
- move state struct definitions to the place where they are being
used
- rate limit some warnings
- use barrier() instead of cpu_relax()
- add/remove some comments
- minor changes like naming of variables
Juergen Gross (3):
xen: clean up xenbus internal headers
xen: modify xenstore watch event interface
xen: optimize xenbus driver for multiple concurrent xenstore accesses
drivers/block/xen-blkback/xenbus.c | 6 +-
drivers/net/xen-netback/xenbus.c | 8 +-
drivers/xen/cpu_hotplug.c | 5 +-
drivers/xen/manage.c | 6 +-
drivers/xen/xen-balloon.c | 2 +-
drivers/xen/xen-pciback/xenbus.c | 2 +-
drivers/xen/xenbus/xenbus.h | 135 +++++++
drivers/xen/xenbus/xenbus_client.c | 6 +-
drivers/xen/xenbus/xenbus_comms.c | 315 +++++++++++++++--
drivers/xen/xenbus/xenbus_comms.h | 51 ---
drivers/xen/xenbus/xenbus_dev_backend.c | 2 +-
drivers/xen/xenbus/xenbus_dev_frontend.c | 213 ++++++-----
drivers/xen/xenbus/xenbus_probe.c | 14 +-
drivers/xen/xenbus/xenbus_probe.h | 88 -----
drivers/xen/xenbus/xenbus_probe_backend.c | 11 +-
drivers/xen/xenbus/xenbus_probe_frontend.c | 17 +-
drivers/xen/xenbus/xenbus_xs.c | 547 +++++++++++++----------------
drivers/xen/xenfs/super.c | 2 +-
drivers/xen/xenfs/xenstored.c | 2 +-
include/xen/xenbus.h | 18 +-
20 files changed, 838 insertions(+), 612 deletions(-)
create mode 100644 drivers/xen/xenbus/xenbus.h
delete mode 100644 drivers/xen/xenbus/xenbus_comms.h
delete mode 100644 drivers/xen/xenbus/xenbus_probe.h
Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com
Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org
--
2.10.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH v2 2/3] xen: modify xenstore watch event interface
2017-01-16 14:15 [PATCH v2 0/3] xen: optimize xenbus performance Juergen Gross
@ 2017-01-16 14:15 ` Juergen Gross
0 siblings, 0 replies; 2+ messages in thread
From: Juergen Gross @ 2017-01-16 14:15 UTC (permalink / raw)
To: linux-kernel, xen-devel
Cc: Juergen Gross, wei.liu2, konrad.wilk, netdev, paul.durrant,
boris.ostrovsky, roger.pau
Today a Xenstore watch event is delivered via a callback function
declared as:
void (*callback)(struct xenbus_watch *,
const char **vec, unsigned int len);
As all watch events only ever come with two parameters (path and token)
changing the prototype to:
void (*callback)(struct xenbus_watch *,
const char *path, const char *token);
is the natural thing to do.
Apply this change and adapt all users.
Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com
Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
drivers/block/xen-blkback/xenbus.c | 6 +++---
drivers/net/xen-netback/xenbus.c | 8 ++++----
drivers/xen/cpu_hotplug.c | 5 ++---
drivers/xen/manage.c | 6 +++---
drivers/xen/xen-balloon.c | 2 +-
drivers/xen/xen-pciback/xenbus.c | 2 +-
drivers/xen/xenbus/xenbus.h | 6 +++---
drivers/xen/xenbus/xenbus_client.c | 4 ++--
drivers/xen/xenbus/xenbus_dev_frontend.c | 21 ++++++++-------------
drivers/xen/xenbus/xenbus_probe.c | 11 ++++-------
drivers/xen/xenbus/xenbus_probe_backend.c | 8 ++++----
drivers/xen/xenbus/xenbus_probe_frontend.c | 14 +++++++-------
drivers/xen/xenbus/xenbus_xs.c | 29 ++++++++++++++---------------
include/xen/xenbus.h | 6 +++---
14 files changed, 59 insertions(+), 69 deletions(-)
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 415e79b..8fe61b5 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -38,8 +38,8 @@ struct backend_info {
static struct kmem_cache *xen_blkif_cachep;
static void connect(struct backend_info *);
static int connect_ring(struct backend_info *);
-static void backend_changed(struct xenbus_watch *, const char **,
- unsigned int);
+static void backend_changed(struct xenbus_watch *, const char *,
+ const char *);
static void xen_blkif_free(struct xen_blkif *blkif);
static void xen_vbd_free(struct xen_vbd *vbd);
@@ -661,7 +661,7 @@ static int xen_blkbk_probe(struct xenbus_device *dev,
* ready, connect.
*/
static void backend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
int err;
unsigned major;
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 3124eae..d8a40fa 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -723,7 +723,7 @@ static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
}
static void xen_net_rate_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
struct xenvif *vif = container_of(watch, struct xenvif, credit_watch);
struct xenbus_device *dev = xenvif_to_xenbus_device(vif);
@@ -780,7 +780,7 @@ static void xen_unregister_credit_watch(struct xenvif *vif)
}
static void xen_mcast_ctrl_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
struct xenvif *vif = container_of(watch, struct xenvif,
mcast_ctrl_watch);
@@ -855,8 +855,8 @@ static void unregister_hotplug_status_watch(struct backend_info *be)
}
static void hotplug_status_changed(struct xenbus_watch *watch,
- const char **vec,
- unsigned int vec_size)
+ const char *path,
+ const char *token)
{
struct backend_info *be = container_of(watch,
struct backend_info,
diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
index 5676aef..7a4daa2 100644
--- a/drivers/xen/cpu_hotplug.c
+++ b/drivers/xen/cpu_hotplug.c
@@ -68,13 +68,12 @@ static void vcpu_hotplug(unsigned int cpu)
}
static void handle_vcpu_hotplug_event(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
unsigned int cpu;
char *cpustr;
- const char *node = vec[XS_WATCH_PATH];
- cpustr = strstr(node, "cpu/");
+ cpustr = strstr(path, "cpu/");
if (cpustr != NULL) {
sscanf(cpustr, "cpu/%u", &cpu);
vcpu_hotplug(cpu);
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
index 26e5e85..ca62c09 100644
--- a/drivers/xen/manage.c
+++ b/drivers/xen/manage.c
@@ -218,7 +218,7 @@ static struct shutdown_handler shutdown_handlers[] = {
};
static void shutdown_handler(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
char *str;
struct xenbus_transaction xbt;
@@ -266,8 +266,8 @@ static void shutdown_handler(struct xenbus_watch *watch,
}
#ifdef CONFIG_MAGIC_SYSRQ
-static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
- unsigned int len)
+static void sysrq_handler(struct xenbus_watch *watch, const char *path,
+ const char *token)
{
char sysrq_key = '\0';
struct xenbus_transaction xbt;
diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
index 79865b8..e7715cb 100644
--- a/drivers/xen/xen-balloon.c
+++ b/drivers/xen/xen-balloon.c
@@ -55,7 +55,7 @@ static int register_balloon(struct device *dev);
/* React to a change in the target key */
static void watch_target(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
unsigned long long new_target;
int err;
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 3f0aee0..3814b44 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -652,7 +652,7 @@ static int xen_pcibk_setup_backend(struct xen_pcibk_device *pdev)
}
static void xen_pcibk_be_watch(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
struct xen_pcibk_device *pdev =
container_of(watch, struct xen_pcibk_device, be_watch);
diff --git a/drivers/xen/xenbus/xenbus.h b/drivers/xen/xenbus/xenbus.h
index a6b007d..5199527 100644
--- a/drivers/xen/xenbus/xenbus.h
+++ b/drivers/xen/xenbus/xenbus.h
@@ -40,8 +40,8 @@ struct xen_bus_type {
int (*get_bus_id)(char bus_id[XEN_BUS_ID_SIZE], const char *nodename);
int (*probe)(struct xen_bus_type *bus, const char *type,
const char *dir);
- void (*otherend_changed)(struct xenbus_watch *watch, const char **vec,
- unsigned int len);
+ void (*otherend_changed)(struct xenbus_watch *watch, const char *path,
+ const char *token);
struct bus_type bus;
};
@@ -84,7 +84,7 @@ int xenbus_dev_resume(struct device *dev);
int xenbus_dev_cancel(struct device *dev);
void xenbus_otherend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len,
+ const char *path, const char *token,
int ignore_on_shutdown);
int xenbus_read_otherend_details(struct xenbus_device *xendev,
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 23edf53..9586c24 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -115,7 +115,7 @@ EXPORT_SYMBOL_GPL(xenbus_strstate);
int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
void (*callback)(struct xenbus_watch *,
- const char **, unsigned int))
+ const char *, const char *))
{
int err;
@@ -153,7 +153,7 @@ EXPORT_SYMBOL_GPL(xenbus_watch_path);
int xenbus_watch_pathfmt(struct xenbus_device *dev,
struct xenbus_watch *watch,
void (*callback)(struct xenbus_watch *,
- const char **, unsigned int),
+ const char *, const char *),
const char *pathfmt, ...)
{
int err;
diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c
index e2bc9b3..e4b9847 100644
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -258,26 +258,23 @@ static struct watch_adapter *alloc_watch_adapter(const char *path,
}
static void watch_fired(struct xenbus_watch *watch,
- const char **vec,
- unsigned int len)
+ const char *path,
+ const char *token)
{
struct watch_adapter *adap;
struct xsd_sockmsg hdr;
- const char *path, *token;
- int path_len, tok_len, body_len, data_len = 0;
+ const char *token_caller;
+ int path_len, tok_len, body_len;
int ret;
LIST_HEAD(staging_q);
adap = container_of(watch, struct watch_adapter, watch);
- path = vec[XS_WATCH_PATH];
- token = adap->token;
+ token_caller = adap->token;
path_len = strlen(path) + 1;
- tok_len = strlen(token) + 1;
- if (len > 2)
- data_len = vec[len] - vec[2] + 1;
- body_len = path_len + tok_len + data_len;
+ tok_len = strlen(token_caller) + 1;
+ body_len = path_len + tok_len;
hdr.type = XS_WATCH_EVENT;
hdr.len = body_len;
@@ -288,9 +285,7 @@ static void watch_fired(struct xenbus_watch *watch,
if (!ret)
ret = queue_reply(&staging_q, path, path_len);
if (!ret)
- ret = queue_reply(&staging_q, token, tok_len);
- if (!ret && len > 2)
- ret = queue_reply(&staging_q, vec[2], data_len);
+ ret = queue_reply(&staging_q, token_caller, tok_len);
if (!ret) {
/* success: pass reply list onto watcher */
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 6baffbb..74888ca 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -169,7 +169,7 @@ int xenbus_read_otherend_details(struct xenbus_device *xendev,
EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
void xenbus_otherend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len,
+ const char *path, const char *token,
int ignore_on_shutdown)
{
struct xenbus_device *dev =
@@ -180,18 +180,15 @@ void xenbus_otherend_changed(struct xenbus_watch *watch,
/* Protect us against watches firing on old details when the otherend
details change, say immediately after a resume. */
if (!dev->otherend ||
- strncmp(dev->otherend, vec[XS_WATCH_PATH],
- strlen(dev->otherend))) {
- dev_dbg(&dev->dev, "Ignoring watch at %s\n",
- vec[XS_WATCH_PATH]);
+ strncmp(dev->otherend, path, strlen(dev->otherend))) {
+ dev_dbg(&dev->dev, "Ignoring watch at %s\n", path);
return;
}
state = xenbus_read_driver_state(dev->otherend);
dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
- state, xenbus_strstate(state), dev->otherend_watch.node,
- vec[XS_WATCH_PATH]);
+ state, xenbus_strstate(state), dev->otherend_watch.node, path);
/*
* Ignore xenbus transitions during shutdown. This prevents us doing
diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c
index f46b4dc..b0bed4f 100644
--- a/drivers/xen/xenbus/xenbus_probe_backend.c
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -181,9 +181,9 @@ static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
}
static void frontend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
- xenbus_otherend_changed(watch, vec, len, 0);
+ xenbus_otherend_changed(watch, path, token, 0);
}
static struct xen_bus_type xenbus_backend = {
@@ -204,11 +204,11 @@ static struct xen_bus_type xenbus_backend = {
};
static void backend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
DPRINTK("");
- xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
+ xenbus_dev_changed(path, &xenbus_backend);
}
static struct xenbus_watch be_watch = {
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index d7b77a6..19e45ce 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -86,9 +86,9 @@ static int xenbus_uevent_frontend(struct device *_dev,
static void backend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
- xenbus_otherend_changed(watch, vec, len, 1);
+ xenbus_otherend_changed(watch, path, token, 1);
}
static void xenbus_frontend_delayed_resume(struct work_struct *w)
@@ -153,11 +153,11 @@ static struct xen_bus_type xenbus_frontend = {
};
static void frontend_changed(struct xenbus_watch *watch,
- const char **vec, unsigned int len)
+ const char *path, const char *token)
{
DPRINTK("");
- xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
+ xenbus_dev_changed(path, &xenbus_frontend);
}
@@ -332,13 +332,13 @@ static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
static int backend_state;
static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
- const char **v, unsigned int l)
+ const char *path, const char *token)
{
- if (xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i",
+ if (xenbus_scanf(XBT_NIL, path, "", "%i",
&backend_state) != 1)
backend_state = XenbusStateUnknown;
printk(KERN_DEBUG "XENBUS: backend %s %s\n",
- v[XS_WATCH_PATH], xenbus_strstate(backend_state));
+ path, xenbus_strstate(backend_state));
wake_up(&backend_state_wq);
}
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index 4c49d87..ebc768f 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -64,8 +64,8 @@ struct xs_stored_msg {
/* Queued watch events. */
struct {
struct xenbus_watch *handle;
- char **vec;
- unsigned int vec_size;
+ const char *path;
+ const char *token;
} watch;
} u;
};
@@ -765,7 +765,7 @@ void unregister_xenbus_watch(struct xenbus_watch *watch)
if (msg->u.watch.handle != watch)
continue;
list_del(&msg->list);
- kfree(msg->u.watch.vec);
+ kfree(msg->u.watch.path);
kfree(msg);
}
spin_unlock(&watch_events_lock);
@@ -833,11 +833,10 @@ static int xenwatch_thread(void *unused)
if (ent != &watch_events) {
msg = list_entry(ent, struct xs_stored_msg, list);
- msg->u.watch.handle->callback(
- msg->u.watch.handle,
- (const char **)msg->u.watch.vec,
- msg->u.watch.vec_size);
- kfree(msg->u.watch.vec);
+ msg->u.watch.handle->callback(msg->u.watch.handle,
+ msg->u.watch.path,
+ msg->u.watch.token);
+ kfree(msg->u.watch.path);
kfree(msg);
}
@@ -903,24 +902,24 @@ static int process_msg(void)
body[msg->hdr.len] = '\0';
if (msg->hdr.type == XS_WATCH_EVENT) {
- msg->u.watch.vec = split(body, msg->hdr.len,
- &msg->u.watch.vec_size);
- if (IS_ERR(msg->u.watch.vec)) {
- err = PTR_ERR(msg->u.watch.vec);
+ if (count_strings(body, msg->hdr.len) != 2) {
+ err = -EINVAL;
kfree(msg);
+ kfree(body);
goto out;
}
+ msg->u.watch.path = (const char *)body;
+ msg->u.watch.token = (const char *)strchr(body, '\0') + 1;
spin_lock(&watches_lock);
- msg->u.watch.handle = find_watch(
- msg->u.watch.vec[XS_WATCH_TOKEN]);
+ msg->u.watch.handle = find_watch(msg->u.watch.token);
if (msg->u.watch.handle != NULL) {
spin_lock(&watch_events_lock);
list_add_tail(&msg->list, &watch_events);
wake_up(&watch_events_waitq);
spin_unlock(&watch_events_lock);
} else {
- kfree(msg->u.watch.vec);
+ kfree(body);
kfree(msg);
}
spin_unlock(&watches_lock);
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index 98f73a2..869c816 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -61,7 +61,7 @@ struct xenbus_watch
/* Callback (executed in a process context with no locks held). */
void (*callback)(struct xenbus_watch *,
- const char **vec, unsigned int len);
+ const char *path, const char *token);
};
@@ -193,11 +193,11 @@ void xenbus_probe(struct work_struct *);
int xenbus_watch_path(struct xenbus_device *dev, const char *path,
struct xenbus_watch *watch,
void (*callback)(struct xenbus_watch *,
- const char **, unsigned int));
+ const char *, const char *));
__printf(4, 5)
int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
void (*callback)(struct xenbus_watch *,
- const char **, unsigned int),
+ const char *, const char *),
const char *pathfmt, ...);
int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
--
2.10.2
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel
^ permalink raw reply related [flat|nested] 2+ messages in thread
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