I'll send out a prototype for comment.
Something like the patch below. The effects of cgroup_disable=foo are:
- foo doesn't show up in /proc/cgroups
- foo isn't auto-mounted if you mount all cgroups in a single hierarchy
- foo isn't visible as an individually mountable subsystem
As a result there will only ever be one call to foo->create(), at init time;
all processes will stay in this group, and the group will never be mounted on a
visible hierarchy. Any additional effects (e.g. not allocating metadata) are up to
the foo subsystem.
This doesn't handle early_init subsystems (their "disabled" bit isn't set be,
but it could easily be extended to do so if any of the early_init systems wanted it - I
think it would just involve some nastier parameter processing since it would occur before
the command-line argument parser had been run.
include/linux/cgroup.h | 1 +
kernel/cgroup.c | 29 +++++++++++++++++++++++++++--
2 files changed, 28 insertions(+), 2 deletions(-)
Index: cgroup_disable-2.6.25-rc2-mm1/include/linux/cgroup.h
===================================================================
--- cgroup_disable-2.6.25-rc2-mm1.orig/include/linux/cgroup.h
+++ cgroup_disable-2.6.25-rc2-mm1/include/linux/cgroup.h
@@ -256,6 +256,7 @@ struct cgroup_subsys {
void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
int subsys_id;
int active;
+ int disabled;
int early_init;
#define MAX_CGROUP_TYPE_NAMELEN 32
const char *name;
Index: cgroup_disable-2.6.25-rc2-mm1/kernel/cgroup.c
===================================================================
--- cgroup_disable-2.6.25-rc2-mm1.orig/kernel/cgroup.c
+++ cgroup_disable-2.6.25-rc2-mm1/kernel/cgroup.c
@@ -790,7 +790,14 @@ static int parse_cgroupfs_options(char *
if (!*token)
return -EINVAL;
if (!strcmp(token, "all")) {
- opts->subsys_bits = (1 << CGROUP_SUBSYS_COUNT) - 1;
+ /* Add all non-disabled subsystems */
+ int i;
+ opts->subsys_bits = 0;
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (!ss->disabled)
+ opts->subsys_bits |= 1ul << i;
+ }
} else if (!strcmp(token, "noprefix")) {
set_bit(ROOT_NOPREFIX, &opts->flags);
} else if (!strncmp(token, "release_agent=", 14)) {
@@ -808,7 +815,8 @@ static int parse_cgroupfs_options(char *
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
ss = subsys[i];
if (!strcmp(token, ss->name)) {
- set_bit(i, &opts->subsys_bits);
+ if (!ss->disabled)
+ set_bit(i, &opts->subsys_bits);
break;
}
}
@@ -2596,6 +2606,8 @@ static int proc_cgroupstats_show(struct
mutex_lock(&cgroup_mutex);
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
+ if (ss->disabled)
+ continue;
seq_printf(m, "%s\t%lu\t%d\n",
ss->name, ss->root->subsys_bits,
ss->root->number_of_cgroups);
@@ -2991,3 +3003,16 @@ static void cgroup_release_agent(struct
spin_unlock(&release_list_lock);
mutex_unlock(&cgroup_mutex);
}
+
+static int __init cgroup_disable(char *str)
+{
+ int i;
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (!strcmp(str, ss->name)) {
+ ss->disabled = 1;
+ break;
+ }
+ }
+}
+__setup("cgroup_disable=", cgroup_disable);
Sure thing, if css has the flag, then it would nice. Could you wrap it up to say
something like css_disabled(&mem_cgroup_subsys)
It's the subsys object rather than the css (cgroup_subsys_state).
We could have something like:
#define cgroup_subsys_disabled(_ss) ((ss_)->disabled)
but I don't see that
cgroup_subsys_disabled(&mem_cgroup_subsys)
is better than just putting
mem_cgroup_subsys.disabled
Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
