Re: [Crash-utility] [PATCH] Improve the ps performance for vmcores with large number of threads

-----Original Message----- > 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(a)redhat.com&gt; Nice, it's a huge improvement in performance! And the patch looks good to me and tested ok. Acked-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; Thanks, Kazu

> --- > 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 > Crash-utility(a)redhat.com > https://listman.redhat.com/mailman/listinfo/crash-utility