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authorLi Zefan <lizefan@huawei.com>2013-03-12 15:36:00 -0700
committerTejun Heo <tj@kernel.org>2013-03-12 15:36:00 -0700
commit6ee211ad0a22869af81eef10845922ac4dcb2d38 (patch)
tree7123b4fd50e0b67c7daf8d243f8b2542eea84e86 /kernel
parentd7eeac1913ff86a17f891cb4b73f03d4b94907d0 (diff)
downloadlinaro-lsk-6ee211ad0a22869af81eef10845922ac4dcb2d38.tar.gz
cgroup: don't bother to resize pid array
When we open cgroup.procs, we'll allocate an buffer and store all tasks' tgid in it, and then duplicate entries will be stripped. If that results in a much smaller pid list, we'll re-allocate a smaller buffer. But we've already sucessfully allocated memory and reading the procs file is a short period and the memory will be freed very soon, so why bother to re-allocate memory. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c37
1 files changed, 3 insertions, 34 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 49297cbc134..29c77a71473 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3400,35 +3400,14 @@ static void pidlist_free(void *p)
else
kfree(p);
}
-static void *pidlist_resize(void *p, int newcount)
-{
- void *newlist;
- /* note: if new alloc fails, old p will still be valid either way */
- if (is_vmalloc_addr(p)) {
- newlist = vmalloc(newcount * sizeof(pid_t));
- if (!newlist)
- return NULL;
- memcpy(newlist, p, newcount * sizeof(pid_t));
- vfree(p);
- } else {
- newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL);
- }
- return newlist;
-}
/*
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
- * If the new stripped list is sufficiently smaller and there's enough memory
- * to allocate a new buffer, will let go of the unneeded memory. Returns the
- * number of unique elements.
+ * Returns the number of unique elements.
*/
-/* is the size difference enough that we should re-allocate the array? */
-#define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new))
-static int pidlist_uniq(pid_t **p, int length)
+static int pidlist_uniq(pid_t *list, int length)
{
int src, dest = 1;
- pid_t *list = *p;
- pid_t *newlist;
/*
* we presume the 0th element is unique, so i starts at 1. trivial
@@ -3449,16 +3428,6 @@ static int pidlist_uniq(pid_t **p, int length)
dest++;
}
after:
- /*
- * if the length difference is large enough, we want to allocate a
- * smaller buffer to save memory. if this fails due to out of memory,
- * we'll just stay with what we've got.
- */
- if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) {
- newlist = pidlist_resize(list, dest);
- if (newlist)
- *p = newlist;
- }
return dest;
}
@@ -3554,7 +3523,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
/* now sort & (if procs) strip out duplicates */
sort(array, length, sizeof(pid_t), cmppid, NULL);
if (type == CGROUP_FILE_PROCS)
- length = pidlist_uniq(&array, length);
+ length = pidlist_uniq(array, length);
l = cgroup_pidlist_find(cgrp, type);
if (!l) {
pidlist_free(array);