Previously, the ps command will iterate over all threads which
have the same tgid, to accumulate their rss value, in order to
get a thread/process's final rss value as part of the final output.
For non-live systems, the rss accumulation values are identical for
threads which have the same tgid, so there is no need to do the
iteration and accumulation repeatly, thus a lot of readmem calls are
skipped. Otherwise it will be the performance bottleneck if the
vmcores have a large number of threads.
In this patch, the rss accumulation value will be stored in a cache,
next time a thread with the same tgid will take it directly without
the iteration.
For example, we can monitor the performance issue when a vmcore has
~65k processes, most of which are threads for several specific
processes. Without the patch, it will take ~7h for ps command
to finish. With the patch, ps command will finish in 1min.
Signed-off-by: Tao Liu <ltao@xxxxxxxxxx>
---
defs.h | 1 +
memory.c | 67 ++++++++++++++++++++++++++++++--------------------------
task.c | 1 +
3 files changed, 38 insertions(+), 31 deletions(-)
diff --git a/defs.h b/defs.h
index b63741c..55600d5 100644
--- a/defs.h
+++ b/defs.h
@@ -829,6 +829,7 @@ struct task_context { /* context stored for each task */
struct tgid_context { /* tgid and task stored for each task */
ulong tgid;
ulong task;
+ long rss_cache;
};
struct task_table { /* kernel/local task table data */
diff --git a/memory.c b/memory.c
index 5af45fd..b930933 100644
--- a/memory.c
+++ b/memory.c
@@ -4665,7 +4665,7 @@ void
get_task_mem_usage(ulong task, struct task_mem_usage *tm)
{
struct task_context *tc;
- long rss = 0;
+ long rss = 0, rss_cache = 0;
BZERO(tm, sizeof(struct task_mem_usage));
@@ -4730,38 +4730,43 @@ get_task_mem_usage(ulong task, struct task_mem_usage *tm)
(last->tgid == (last + 1)->tgid))
last++;
- while (first <= last)
- {
- /* count 0 -> filepages */
- if (!readmem(first->task +
- OFFSET(task_struct_rss_stat) +
- OFFSET(task_rss_stat_count), KVADDR,
- &sync_rss,
- sizeof(int),
- "task_struct rss_stat MM_FILEPAGES",
- RETURN_ON_ERROR))
- continue;
-
- rss += sync_rss;
-
- /* count 1 -> anonpages */
- if (!readmem(first->task +
- OFFSET(task_struct_rss_stat) +
- OFFSET(task_rss_stat_count) +
- sizeof(int),
- KVADDR, &sync_rss,
- sizeof(int),
- "task_struct rss_stat MM_ANONPAGES",
- RETURN_ON_ERROR))
- continue;
-
- rss += sync_rss;
-
- if (first == last)
- break;
- first++;
+ /* We will use rss_cache only for dumpfile */
+ if (ACTIVE() || last->rss_cache == UNINITIALIZED) {
+ while (first <= last)
+ {
+ /* count 0 -> filepages */
+ if (!readmem(first->task +
+ OFFSET(task_struct_rss_stat) +
+ OFFSET(task_rss_stat_count), KVADDR,
+ &sync_rss,
+ sizeof(int),
+ "task_struct rss_stat MM_FILEPAGES",
+ RETURN_ON_ERROR))
+ continue;
+
+ rss_cache += sync_rss;
+
+ /* count 1 -> anonpages */
+ if (!readmem(first->task +
+ OFFSET(task_struct_rss_stat) +
+ OFFSET(task_rss_stat_count) +
+ sizeof(int),
+ KVADDR, &sync_rss,
+ sizeof(int),
+ "task_struct rss_stat MM_ANONPAGES",
+ RETURN_ON_ERROR))
+ continue;
+
+ rss_cache += sync_rss;
+
+ if (first == last)
+ break;
+ first++;
+ }
+ last->rss_cache = rss_cache;
}
+ rss += last->rss_cache;
tt->last_tgid = last;
}
}
diff --git a/task.c b/task.c
index 263a834..9868a6e 100644
--- a/task.c
+++ b/task.c
@@ -2947,6 +2947,7 @@ add_context(ulong task, char *tp)
tg = tt->tgid_array + tt->running_tasks;
tg->tgid = *tgid_addr;
tg->task = task;
+ tg->rss_cache = UNINITIALIZED;
if (do_verify && !verify_task(tc, do_verify)) {
error(INFO, "invalid task address: %lx\n", tc->task);
--
2.33.1
--
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