* [PATCH] perf: Replace malloc with alloca in hot path
@ 2012-01-30 19:07 Santosh Jodh
2012-02-01 16:14 ` Ian Campbell
0 siblings, 1 reply; 4+ messages in thread
From: Santosh Jodh @ 2012-01-30 19:07 UTC (permalink / raw)
To: xen-devel; +Cc: ian.campbell
Replace malloc with alloc in hot paths for improved performance.
Signed-off-by: Santosh Jodh <santosh.jodh@citrix.com>
diff -r e2722b24dc09 -r 4952090d35e0 tools/libxc/xc_linux_osdep.c
--- a/tools/libxc/xc_linux_osdep.c Thu Jan 26 17:43:31 2012 +0000
+++ b/tools/libxc/xc_linux_osdep.c Mon Jan 30 11:02:32 2012 -0800
@@ -242,7 +242,7 @@ static void *linux_privcmd_map_foreign_b
* IOCTL_PRIVCMD_MMAPBATCH_V2 is not supported - fall back to
* IOCTL_PRIVCMD_MMAPBATCH.
*/
- xen_pfn_t *pfn = malloc(num * sizeof(*pfn));
+ xen_pfn_t *pfn = alloca(num * sizeof(*pfn));
if ( pfn )
{
@@ -288,8 +288,6 @@ static void *linux_privcmd_map_foreign_b
break;
}
- free(pfn);
-
if ( rc == -ENOENT && i == num )
rc = 0;
else if ( rc )
@@ -524,7 +522,7 @@ static void *linux_gnttab_grant_map(xc_g
if (flags & XC_GRANT_MAP_SINGLE_DOMAIN)
domids_stride = 0;
- map = malloc(sizeof(*map) +
+ map = alloca(sizeof(*map) +
(count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
if ( map == NULL )
return NULL;
@@ -598,7 +596,6 @@ static void *linux_gnttab_grant_map(xc_g
}
out:
- free(map);
return addr;
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] perf: Replace malloc with alloca in hot path
2012-01-30 19:07 [PATCH] perf: Replace malloc with alloca in hot path Santosh Jodh
@ 2012-02-01 16:14 ` Ian Campbell
2012-02-01 16:19 ` Santosh Jodh
2012-02-07 18:46 ` Ian Jackson
0 siblings, 2 replies; 4+ messages in thread
From: Ian Campbell @ 2012-02-01 16:14 UTC (permalink / raw)
To: Santosh Jodh; +Cc: xen-devel
On Mon, 2012-01-30 at 19:07 +0000, Santosh Jodh wrote:
> Replace malloc with alloc in hot paths for improved performance.
This is a hot path in something like a userspace PV backend which is
frequently mapping guest domain pages, or something like that?
> Signed-off-by: Santosh Jodh <santosh.jodh@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
>
> diff -r e2722b24dc09 -r 4952090d35e0 tools/libxc/xc_linux_osdep.c
> --- a/tools/libxc/xc_linux_osdep.c Thu Jan 26 17:43:31 2012 +0000
> +++ b/tools/libxc/xc_linux_osdep.c Mon Jan 30 11:02:32 2012 -0800
> @@ -242,7 +242,7 @@ static void *linux_privcmd_map_foreign_b
> * IOCTL_PRIVCMD_MMAPBATCH_V2 is not supported - fall back to
> * IOCTL_PRIVCMD_MMAPBATCH.
> */
> - xen_pfn_t *pfn = malloc(num * sizeof(*pfn));
> + xen_pfn_t *pfn = alloca(num * sizeof(*pfn));
>
> if ( pfn )
> {
> @@ -288,8 +288,6 @@ static void *linux_privcmd_map_foreign_b
> break;
> }
>
> - free(pfn);
> -
> if ( rc == -ENOENT && i == num )
> rc = 0;
> else if ( rc )
> @@ -524,7 +522,7 @@ static void *linux_gnttab_grant_map(xc_g
> if (flags & XC_GRANT_MAP_SINGLE_DOMAIN)
> domids_stride = 0;
>
> - map = malloc(sizeof(*map) +
> + map = alloca(sizeof(*map) +
> (count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
> if ( map == NULL )
> return NULL;
> @@ -598,7 +596,6 @@ static void *linux_gnttab_grant_map(xc_g
> }
>
> out:
> - free(map);
>
> return addr;
> }
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] perf: Replace malloc with alloca in hot path
2012-02-01 16:14 ` Ian Campbell
@ 2012-02-01 16:19 ` Santosh Jodh
2012-02-07 18:46 ` Ian Jackson
1 sibling, 0 replies; 4+ messages in thread
From: Santosh Jodh @ 2012-02-01 16:19 UTC (permalink / raw)
To: Ian Campbell; +Cc: xen-devel
Yes - that is correct. This is used in the IO path for user mode block backend.
Thanks,
Santosh
-----Original Message-----
From: Ian Campbell
Sent: Wednesday, February 01, 2012 8:15 AM
To: Santosh Jodh
Cc: xen-devel@lists.xensource.com
Subject: Re: [PATCH] perf: Replace malloc with alloca in hot path
On Mon, 2012-01-30 at 19:07 +0000, Santosh Jodh wrote:
> Replace malloc with alloc in hot paths for improved performance.
This is a hot path in something like a userspace PV backend which is frequently mapping guest domain pages, or something like that?
> Signed-off-by: Santosh Jodh <santosh.jodh@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
>
> diff -r e2722b24dc09 -r 4952090d35e0 tools/libxc/xc_linux_osdep.c
> --- a/tools/libxc/xc_linux_osdep.c Thu Jan 26 17:43:31 2012 +0000
> +++ b/tools/libxc/xc_linux_osdep.c Mon Jan 30 11:02:32 2012 -0800
> @@ -242,7 +242,7 @@ static void *linux_privcmd_map_foreign_b
> * IOCTL_PRIVCMD_MMAPBATCH_V2 is not supported - fall back to
> * IOCTL_PRIVCMD_MMAPBATCH.
> */
> - xen_pfn_t *pfn = malloc(num * sizeof(*pfn));
> + xen_pfn_t *pfn = alloca(num * sizeof(*pfn));
>
> if ( pfn )
> {
> @@ -288,8 +288,6 @@ static void *linux_privcmd_map_foreign_b
> break;
> }
>
> - free(pfn);
> -
> if ( rc == -ENOENT && i == num )
> rc = 0;
> else if ( rc )
> @@ -524,7 +522,7 @@ static void *linux_gnttab_grant_map(xc_g
> if (flags & XC_GRANT_MAP_SINGLE_DOMAIN)
> domids_stride = 0;
>
> - map = malloc(sizeof(*map) +
> + map = alloca(sizeof(*map) +
> (count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
> if ( map == NULL )
> return NULL;
> @@ -598,7 +596,6 @@ static void *linux_gnttab_grant_map(xc_g
> }
>
> out:
> - free(map);
>
> return addr;
> }
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] perf: Replace malloc with alloca in hot path
2012-02-01 16:14 ` Ian Campbell
2012-02-01 16:19 ` Santosh Jodh
@ 2012-02-07 18:46 ` Ian Jackson
1 sibling, 0 replies; 4+ messages in thread
From: Ian Jackson @ 2012-02-07 18:46 UTC (permalink / raw)
To: Ian Campbell; +Cc: xen-devel, Santosh Jodh
Ian Campbell writes ("Re: [Xen-devel] [PATCH] perf: Replace malloc with alloca in hot path"):
> On Mon, 2012-01-30 at 19:07 +0000, Santosh Jodh wrote:
> > Replace malloc with alloc in hot paths for improved performance.
>
> This is a hot path in something like a userspace PV backend which is
> frequently mapping guest domain pages, or something like that?
>
> > Signed-off-by: Santosh Jodh <santosh.jodh@citrix.com>
>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-02-07 18:46 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2012-01-30 19:07 [PATCH] perf: Replace malloc with alloca in hot path Santosh Jodh
2012-02-01 16:14 ` Ian Campbell
2012-02-01 16:19 ` Santosh Jodh
2012-02-07 18:46 ` Ian Jackson
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