* Re: [PATCH] uevent_can_discard: optimize devpath check
@ 2017-03-02 8:35 tang.junhui
0 siblings, 0 replies; 3+ messages in thread
From: tang.junhui @ 2017-03-02 8:35 UTC (permalink / raw)
To: mwilck; +Cc: dm-devel
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It looks fine to me.
Regards,
Tang Junhui
＞ This uses roughly 10% cycles of the sscanf-based implementation.
＞
＞ Improves: ee8888f0 "multipath-tools: improve processing efficiency..."
＞ Signed-off-by: Martin Wilck ＜mwilck@suse.com＞
＞ ---
＞ libmultipath/uevent.c | 37 +++++++++++++++++++++++--------------
＞ 1 file changed, 23 insertions(+), 14 deletions(-)
＞
＞ diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
＞ index 6e2527bd..367e129a 100644
＞ --- a/libmultipath/uevent.c
＞ +++ b/libmultipath/uevent.c
＞ @@ -143,26 +143,35 @@ uevent_need_merge(void)
＞ return need_merge
＞ }
＞
＞ +static bool
＞ +uevent_can_discard_by_devpath(const char *devpath)
＞ +{
＞ + static const char BLOCK[] = "/block/"
＞ + const char *tmp = strstr(devpath, BLOCK)
＞ +
＞ + if (tmp == NULL) {
＞ + condlog(4, "no /block/ in '%s'", devpath)
＞ + return true
＞ + }
＞ + tmp += sizeof(BLOCK) - 1
＞ + if (*tmp == '\0')
＞ + /* just ".../block/" - discard */
＞ + return true
＞ + /*
＞ + * If there are more path elements after ".../block/xyz",
＞ + * it's a partition - discard it but don't discard ".../block/sda/".
＞ + */
＞ + tmp = strchr(tmp, '/')
＞ + return tmp != NULL && *(tmp + 1) != '\0'
＞ +}
＞ +
＞ bool
＞ uevent_can_discard(struct uevent *uev)
＞ {
＞ - char *tmp
＞ - char a[11], b[11]
＞ struct config * conf
＞
＞ - /*
＞ - * keep only block devices, discard partitions
＞ - */
＞ - tmp = strstr(uev-＞devpath, "/block/")
＞ - if (tmp == NULL){
＞ - condlog(4, "no /block/ in '%s'", uev-＞devpath)
＞ + if (uevent_can_discard_by_devpath(uev-＞devpath))
＞ return true
＞ - }
＞ - if (sscanf(tmp, "/block/%10s", a) != 1 ||
＞ - sscanf(tmp, "/block/%10[^/]/%10s", a, b) == 2) {
＞ - condlog(4, "discard event on %s", uev-＞devpath)
＞ - return true
＞ - }
＞
＞ /*
＞ * do not filter dm devices by devnode
＞ --
＞ 2.12.0
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^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH] uevent_can_discard: optimize devpath check
@ 2017-03-01 17:22 Martin Wilck
2017-03-16 6:42 ` Christophe Varoqui
0 siblings, 1 reply; 3+ messages in thread
From: Martin Wilck @ 2017-03-01 17:22 UTC (permalink / raw)
To: tang.junhui, dm-devel
This uses roughly 10% cycles of the sscanf-based implementation.
Improves: ee8888f0 "multipath-tools: improve processing efficiency..."
Signed-off-by: Martin Wilck <mwilck@suse.com>
---
libmultipath/uevent.c | 37 +++++++++++++++++++++++--------------
1 file changed, 23 insertions(+), 14 deletions(-)
diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
index 6e2527bd..367e129a 100644
--- a/libmultipath/uevent.c
+++ b/libmultipath/uevent.c
@@ -143,26 +143,35 @@ uevent_need_merge(void)
return need_merge;
}
+static bool
+uevent_can_discard_by_devpath(const char *devpath)
+{
+ static const char BLOCK[] = "/block/";
+ const char *tmp = strstr(devpath, BLOCK);
+
+ if (tmp == NULL) {
+ condlog(4, "no /block/ in '%s'", devpath);
+ return true;
+ }
+ tmp += sizeof(BLOCK) - 1;
+ if (*tmp == '\0')
+ /* just ".../block/" - discard */
+ return true;
+ /*
+ * If there are more path elements after ".../block/xyz",
+ * it's a partition - discard it; but don't discard ".../block/sda/".
+ */
+ tmp = strchr(tmp, '/');
+ return tmp != NULL && *(tmp + 1) != '\0';
+}
+
bool
uevent_can_discard(struct uevent *uev)
{
- char *tmp;
- char a[11], b[11];
struct config * conf;
- /*
- * keep only block devices, discard partitions
- */
- tmp = strstr(uev->devpath, "/block/");
- if (tmp == NULL){
- condlog(4, "no /block/ in '%s'", uev->devpath);
+ if (uevent_can_discard_by_devpath(uev->devpath))
return true;
- }
- if (sscanf(tmp, "/block/%10s", a) != 1 ||
- sscanf(tmp, "/block/%10[^/]/%10s", a, b) == 2) {
- condlog(4, "discard event on %s", uev->devpath);
- return true;
- }
/*
* do not filter dm devices by devnode
--
2.12.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] uevent_can_discard: optimize devpath check
2017-03-01 17:22 Martin Wilck
@ 2017-03-16 6:42 ` Christophe Varoqui
0 siblings, 0 replies; 3+ messages in thread
From: Christophe Varoqui @ 2017-03-16 6:42 UTC (permalink / raw)
To: Martin Wilck; +Cc: device-mapper development, tang.junhui
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Applied.
Thanks.
On Wed, Mar 1, 2017 at 6:22 PM, Martin Wilck <mwilck@suse.com> wrote:
> This uses roughly 10% cycles of the sscanf-based implementation.
>
> Improves: ee8888f0 "multipath-tools: improve processing efficiency..."
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> ---
> libmultipath/uevent.c | 37 +++++++++++++++++++++++--------------
> 1 file changed, 23 insertions(+), 14 deletions(-)
>
> diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
> index 6e2527bd..367e129a 100644
> --- a/libmultipath/uevent.c
> +++ b/libmultipath/uevent.c
> @@ -143,26 +143,35 @@ uevent_need_merge(void)
> return need_merge;
> }
>
> +static bool
> +uevent_can_discard_by_devpath(const char *devpath)
> +{
> + static const char BLOCK[] = "/block/";
> + const char *tmp = strstr(devpath, BLOCK);
> +
> + if (tmp == NULL) {
> + condlog(4, "no /block/ in '%s'", devpath);
> + return true;
> + }
> + tmp += sizeof(BLOCK) - 1;
> + if (*tmp == '\0')
> + /* just ".../block/" - discard */
> + return true;
> + /*
> + * If there are more path elements after ".../block/xyz",
> + * it's a partition - discard it; but don't discard
> ".../block/sda/".
> + */
> + tmp = strchr(tmp, '/');
> + return tmp != NULL && *(tmp + 1) != '\0';
> +}
> +
> bool
> uevent_can_discard(struct uevent *uev)
> {
> - char *tmp;
> - char a[11], b[11];
> struct config * conf;
>
> - /*
> - * keep only block devices, discard partitions
> - */
> - tmp = strstr(uev->devpath, "/block/");
> - if (tmp == NULL){
> - condlog(4, "no /block/ in '%s'", uev->devpath);
> + if (uevent_can_discard_by_devpath(uev->devpath))
> return true;
> - }
> - if (sscanf(tmp, "/block/%10s", a) != 1 ||
> - sscanf(tmp, "/block/%10[^/]/%10s", a, b) == 2) {
> - condlog(4, "discard event on %s", uev->devpath);
> - return true;
> - }
>
> /*
> * do not filter dm devices by devnode
> --
> 2.12.0
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
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2017-03-16 6:42 ` Christophe Varoqui
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