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 <[email protected]> --- 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 -- Crash-utility mailing list [email protected] https://listman.redhat.com/mailman/listinfo/crash-utility
