kernel.git/include/trace/events/vmscan.h, branch linux-4.12.y

mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint

2017-02-23T00:41:29Z

Currently we have tracepoints for both active and inactive LRU lists reclaim but we do not have any which would tell us why we we decided to age the active list. Without that it is quite hard to diagnose active/inactive lists balancing. Add mm_vmscan_inactive_list_is_low tracepoint to tell us this information. Link: http://lkml.kernel.org/r/20170104101942.4860-8-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Hillf Danton Acked-by: Mel Gorman Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint

2017-02-23T00:41:29Z

mm_vmscan_lru_shrink_inactive will currently report the number of scanned and reclaimed pages. This doesn't give us an idea how the reclaim went except for the overall effectiveness though. Export and show other counters which will tell us why we couldn't reclaim some pages. - nr_dirty, nr_writeback, nr_congested and nr_immediate tells us how many pages are blocked due to IO - nr_activate tells us how many pages were moved to the active list - nr_ref_keep reports how many pages are kept on the LRU due to references (mostly for the file pages which are about to go for another round through the inactive list) - nr_unmap_fail - how many pages failed to unmap All these are rather low level so they might change in future but the tracepoint is already implementation specific so no tools should be depending on its stability. Link: http://lkml.kernel.org/r/20170104101942.4860-7-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Hillf Danton Acked-by: Mel Gorman Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint

2017-02-23T00:41:29Z

mm_vmscan_lru_isolate currently prints only whether the LRU we isolate from is file or anonymous but we do not know which LRU this is. It is useful to know whether the list is active or inactive, since we are using the same function to isolate pages from both of them and it's hard to distinguish otherwise. Link: http://lkml.kernel.org/r/20170104101942.4860-5-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Hillf Danton Acked-by: Mel Gorman Acked-by: Minchan Kim Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate

2017-02-23T00:41:29Z

mm_vmscan_lru_isolate shows the number of requested, scanned and taken pages. This is mostly OK but on 32b systems the number of scanned pages is quite misleading because it includes both the scanned and skipped pages. Moreover the skipped part is scaled based on the number of taken pages. Let's report the exact numbers without any additional logic and add the number of skipped pages. This should make the reported data much more easier to interpret. Link: http://lkml.kernel.org/r/20170104101942.4860-4-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Minchan Kim Acked-by: Mel Gorman Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: add active list aging tracepoint

2017-02-23T00:41:29Z

Our reclaim process has several tracepoints to tell us more about how things are progressing. We are, however, missing a tracepoint to track active list aging. Introduce mm_vmscan_lru_shrink_active which reports the number of - nr_taken is number of isolated pages from the active list - nr_referenced pages which tells us that we are hitting referenced pages which are deactivated. If this is a large part of the reported nr_deactivated pages then we might be hitting into the active list too early because they might be still part of the working set. This might help to debug performance issues. - nr_active pages which tells us how many pages are kept on the active list - mostly exec file backed pages. A high number can indicate that we might be trashing on executables. [mhocko@suse.com: update] Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Hillf Danton Acked-by: Mel Gorman Acked-by: Minchan Kim Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: remove unused mm_vmscan_memcg_isolate

2017-02-23T00:41:29Z

Patch series "vm, vmscan: enahance vmscan tracepoints", v2. While debugging [2] I've realized that there is some room for improvements in the tracepoints set we offer currently. I had hard times to make any conclusion from the existing ones. The resulting problem turned out to be active list aging [3] and we are missing at least two tracepoints to debug such a problem. Some existing tracepoints could export more information to see _why_ the reclaim progress cannot be made not only _how much_ we could reclaim. The later could be seen quite reasonably from the vmstat counters already. It can be argued that we are showing too many implementation details in those tracepoints but I consider them way too lowlevel already to be usable by any kernel independent userspace. I would be _really_ surprised if anything but debugging tools have used them. Any feedback is highly appreciated. [1] http://lkml.kernel.org/r/20161228153032.10821-1-mhocko@kernel.org [2] http://lkml.kernel.org/r/20161215225702.GA27944@boerne.fritz.box [3] http://lkml.kernel.org/r/20161223105157.GB23109@dhcp22.suse.cz This patch (of 8): The trace point is not used since 925b7673cce3 ("mm: make per-memcg LRU lists exclusive") so it can be removed. Link: http://lkml.kernel.org/r/20170104101942.4860-2-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Hillf Danton Acked-by: Mel Gorman Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: add classzone information to tracepoints

2016-07-28T23:07:41Z

This is convenient when tracking down why the skip count is high because it'll show what classzone kswapd woke up at and what zones are being isolated. Link: http://lkml.kernel.org/r/1467970510-21195-29-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Cc: Hillf Danton Acked-by: Johannes Weiner Cc: Joonsoo Kim Cc: Michal Hocko Cc: Minchan Kim Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, vmscan: move LRU lists to node

2016-07-28T23:07:41Z

This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Johannes Weiner Acked-by: Vlastimil Babka Cc: Hillf Danton Cc: Joonsoo Kim Cc: Michal Hocko Cc: Minchan Kim Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, tracing: unify mm flags handling in tracepoints and printk

2016-03-15T23:55:16Z

In tracepoints, it's possible to print gfp flags in a human-friendly format through a macro show_gfp_flags(), which defines a translation array and passes is to __print_flags(). Since the following patch will introduce support for gfp flags printing in printk(), it would be nice to reuse the array. This is not straightforward, since __print_flags() can't simply reference an array defined in a .c file such as mm/debug.c - it has to be a macro to allow the macro magic to communicate the format to userspace tools such as trace-cmd. The solution is to create a macro __def_gfpflag_names which is used both in show_gfp_flags(), and to define the gfpflag_names[] array in mm/debug.c. On the other hand, mm/debug.c also defines translation tables for page flags and vma flags, and desire was expressed (but not implemented in this series) to use these also from tracepoints. Thus, this patch also renames the events/gfpflags.h file to events/mmflags.h and moves the table definitions there, using the same macro approach as for gfpflags. This allows translating all three kinds of mm-specific flags both in tracepoints and printk. Signed-off-by: Vlastimil Babka Reviewed-by: Michal Hocko Cc: Steven Rostedt Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Rasmus Villemoes Cc: Joonsoo Kim Cc: Minchan Kim Cc: Sasha Levin Cc: "Kirill A. Shutemov" Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: change mm_vmscan_lru_shrink_inactive() proto types

2016-01-15T00:00:49Z

Move node_id zone_idx shrink flags into trace function, so thay we don't need caculate these args if the trace is disabled, and will make this function have less arguments. Signed-off-by: yalin wang Reviewed-by: Steven Rostedt Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds