[systemd-commits] 2 commits - TODO src/readahead src/shared
Lennart Poettering
lennart at kemper.freedesktop.org
Thu May 3 15:14:46 PDT 2012
TODO | 2
src/readahead/readahead-collect.c | 33 ++++++++++++---
src/readahead/readahead-common.c | 82 +++++++++++++++++++++++++++++++++++++-
src/readahead/readahead-common.h | 5 +-
src/readahead/readahead-replay.c | 2
src/shared/cgroup-util.c | 33 +++++++++++----
6 files changed, 138 insertions(+), 19 deletions(-)
New commits:
commit 6de338a2d9904ef5a67552b024491700523074a3
Author: Lennart Poettering <lennart at poettering.net>
Date: Fri May 4 00:13:20 2012 +0200
readhead: temporarily lower the kernel's read_ahead_kb setting while collecting
While collecting readahead data we want to know exactly what userspace
accesses unblurred by the kernel's read_ahead_kb. Hence lower this
during collection, and raise it afterwards.
This is mostly based on ideas and code by Auke Kok.
diff --git a/src/readahead/readahead-collect.c b/src/readahead/readahead-collect.c
index 008ede3..70e0f66 100644
--- a/src/readahead/readahead-collect.c
+++ b/src/readahead/readahead-collect.c
@@ -233,9 +233,26 @@ static int collect(const char *root) {
bool on_ssd, on_btrfs;
struct statfs sfs;
usec_t not_after;
+ uint64_t previous_block_readahead;
+ bool previous_block_readahead_set = false;
assert(root);
+ if (asprintf(&pack_fn, "%s/.readahead", root) < 0) {
+ log_error("Out of memory");
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ /* If there's no pack file yet we lower the kernel readahead
+ * so that mincore() is accurate. If there is a pack file
+ * already we assume it is accurate enough so that kernel
+ * readahead is never triggered. */
+ previous_block_readahead_set =
+ access(pack_fn, F_OK) < 0 &&
+ block_get_readahead(root, &previous_block_readahead) >= 0 &&
+ block_set_readahead(root, 8*1024) >= 0;
+
write_one_line_file("/proc/self/oom_score_adj", "1000");
if (ioprio_set(IOPRIO_WHO_PROCESS, getpid(), IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)) < 0)
@@ -458,10 +475,7 @@ done:
on_btrfs = statfs(root, &sfs) >= 0 && (long) sfs.f_type == (long) BTRFS_SUPER_MAGIC;
log_debug("On btrfs: %s", yes_no(on_btrfs));
- asprintf(&pack_fn, "%s/.readahead", root);
- asprintf(&pack_fn_new, "%s/.readahead.new", root);
-
- if (!pack_fn || !pack_fn_new) {
+ if (asprintf(&pack_fn_new, "%s/.readahead.new", root) < 0) {
log_error("Out of memory");
r = -ENOMEM;
goto finish;
@@ -551,7 +565,6 @@ finish:
fclose(pack);
unlink(pack_fn_new);
}
-
free(pack_fn_new);
free(pack_fn);
@@ -560,6 +573,16 @@ finish:
hashmap_free(files);
+ if (previous_block_readahead_set) {
+ uint64_t bytes;
+
+ /* Restore the original kernel readahead setting if we
+ * changed it, and nobody has overwritten it since
+ * yet. */
+ if (block_get_readahead(root, &bytes) >= 0 && bytes == 8*1024)
+ block_set_readahead(root, previous_block_readahead);
+ }
+
return r;
}
diff --git a/src/readahead/readahead-common.c b/src/readahead/readahead-common.c
index 4e8e636..99dbac2 100644
--- a/src/readahead/readahead-common.c
+++ b/src/readahead/readahead-common.c
@@ -210,7 +210,7 @@ finish:
#define BUMP_REQUEST_NR (16*1024)
-int bump_request_nr(const char *p) {
+int block_bump_request_nr(const char *p) {
struct stat st;
uint64_t u;
char *ap = NULL, *line = NULL;
@@ -267,3 +267,83 @@ finish:
return r;
}
+
+int block_get_readahead(const char *p, uint64_t *bytes) {
+ struct stat st;
+ char *ap = NULL, *line = NULL;
+ int r;
+ dev_t d;
+ uint64_t u;
+
+ assert(p);
+ assert(bytes);
+
+ if (stat(p, &st) < 0)
+ return -errno;
+
+ if (major(st.st_dev) == 0)
+ return 0;
+
+ d = st.st_dev;
+ block_get_whole_disk(d, &d);
+
+ if (asprintf(&ap, "/sys/dev/block/%u:%u/bdi/read_ahead_kb", major(d), minor(d)) < 0) {
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ r = read_one_line_file(ap, &line);
+ if (r < 0)
+ goto finish;
+
+ r = safe_atou64(line, &u);
+ if (r < 0)
+ goto finish;
+
+ *bytes = u * 1024ULL;
+
+finish:
+ free(ap);
+ free(line);
+
+ return r;
+}
+
+int block_set_readahead(const char *p, uint64_t bytes) {
+ struct stat st;
+ char *ap = NULL, *line = NULL;
+ int r;
+ dev_t d;
+
+ assert(p);
+ assert(bytes);
+
+ if (stat(p, &st) < 0)
+ return -errno;
+
+ if (major(st.st_dev) == 0)
+ return 0;
+
+ d = st.st_dev;
+ block_get_whole_disk(d, &d);
+
+ if (asprintf(&ap, "/sys/dev/block/%u:%u/bdi/read_ahead_kb", major(d), minor(d)) < 0) {
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ if (asprintf(&line, "%llu", (unsigned long long) bytes / 1024ULL) < 0) {
+ r = -ENOMEM;
+ goto finish;
+ }
+
+ r = write_one_line_file(ap, line);
+ if (r < 0)
+ goto finish;
+
+finish:
+ free(ap);
+ free(line);
+
+ return r;
+}
diff --git a/src/readahead/readahead-common.h b/src/readahead/readahead-common.h
index b4eab71..9962dd5 100644
--- a/src/readahead/readahead-common.h
+++ b/src/readahead/readahead-common.h
@@ -45,6 +45,9 @@ typedef struct ReadaheadShared {
ReadaheadShared *shared_get(void);
-int bump_request_nr(const char *p);
+int block_bump_request_nr(const char *p);
+
+int block_get_readahead(const char *p, uint64_t *bytes);
+int block_set_readahead(const char *p, uint64_t bytes);
#endif
diff --git a/src/readahead/readahead-replay.c b/src/readahead/readahead-replay.c
index f91020e..0b7e6df 100644
--- a/src/readahead/readahead-replay.c
+++ b/src/readahead/readahead-replay.c
@@ -133,7 +133,7 @@ static int replay(const char *root) {
assert(root);
write_one_line_file("/proc/self/oom_score_adj", "1000");
- bump_request_nr(root);
+ block_bump_request_nr(root);
if (asprintf(&pack_fn, "%s/.readahead", root) < 0) {
log_error("Out of memory");
commit 37099707e26ef2c6d215f6e7f17dd46bf6aad586
Author: Lennart Poettering <lennart at poettering.net>
Date: Thu May 3 23:23:38 2012 +0200
cgroup: fix alloca() misuse in cg_shorten_controllers()
diff --git a/TODO b/TODO
index 2e33360..f2c5dd6 100644
--- a/TODO
+++ b/TODO
@@ -60,8 +60,6 @@ Features:
* add RequiredBy to [Install]
-* cg_shorten_controllers() misuses alloca()
-
* udev: move to LGPL
* udev systemd unify:
diff --git a/src/shared/cgroup-util.c b/src/shared/cgroup-util.c
index d34c142..1f310d3 100644
--- a/src/shared/cgroup-util.c
+++ b/src/shared/cgroup-util.c
@@ -565,9 +565,23 @@ int cg_get_path(const char *controller, const char *path, const char *suffix, ch
return join_path(p, path, suffix, fs);
}
+static int check(const char *p) {
+ char *cc;
+
+ assert(p);
+
+ /* Check if this controller actually really exists */
+ cc = alloca(sizeof("/sys/fs/cgroup/") + strlen(p));
+ strcpy(stpcpy(cc, "/sys/fs/cgroup/"), p);
+ if (access(cc, F_OK) < 0)
+ return -errno;
+
+ return 0;
+}
+
int cg_get_path_and_check(const char *controller, const char *path, const char *suffix, char **fs) {
const char *p;
- char *cc;
+ int r;
assert(controller);
assert(fs);
@@ -575,13 +589,13 @@ int cg_get_path_and_check(const char *controller, const char *path, const char *
if (isempty(controller))
return -EINVAL;
+ /* Normalize the controller syntax */
p = normalize_controller(controller);
/* Check if this controller actually really exists */
- cc = alloca(sizeof("/sys/fs/cgroup/") + strlen(p));
- strcpy(stpcpy(cc, "/sys/fs/cgroup/"), p);
- if (access(cc, F_OK) < 0)
- return -errno;
+ r = check(p);
+ if (r < 0)
+ return r;
return join_path(p, path, suffix, fs);
}
@@ -1111,17 +1125,18 @@ char **cg_shorten_controllers(char **controllers) {
return controllers;
for (f = controllers, t = controllers; *f; f++) {
- char *cc;
+ int r;
+ const char *p;
if (streq(*f, "systemd") || streq(*f, SYSTEMD_CGROUP_CONTROLLER)) {
free(*f);
continue;
}
- cc = alloca(sizeof("/sys/fs/cgroup/") + strlen(*f));
- strcpy(stpcpy(cc, "/sys/fs/cgroup/"), *f);
+ p = normalize_controller(*f);
- if (access(cc, F_OK) < 0) {
+ r = check(p);
+ if (r < 0) {
log_debug("Controller %s is not available, removing from controllers list.", *f);
free(*f);
continue;
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