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@@ -1,6 +1,6 @@
1Memory Resource Controller(Memcg) Implementation Memo. 1Memory Resource Controller(Memcg) Implementation Memo.
2Last Updated: 2009/1/20 2Last Updated: 2010/2
3Base Kernel Version: based on 2.6.29-rc2. 3Base Kernel Version: based on 2.6.33-rc7-mm(candidate for 34).
4 4
5Because VM is getting complex (one of reasons is memcg...), memcg's behavior 5Because VM is getting complex (one of reasons is memcg...), memcg's behavior
6is complex. This is a document for memcg's internal behavior. 6is complex. This is a document for memcg's internal behavior.
@@ -244,7 +244,7 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
244 we have to check if OLDPAGE/NEWPAGE is a valid page after commit(). 244 we have to check if OLDPAGE/NEWPAGE is a valid page after commit().
245 245
2468. LRU 2468. LRU
247 Each memcg has its own private LRU. Now, it's handling is under global 247 Each memcg has its own private LRU. Now, its handling is under global
248 VM's control (means that it's handled under global zone->lru_lock). 248 VM's control (means that it's handled under global zone->lru_lock).
249 Almost all routines around memcg's LRU is called by global LRU's 249 Almost all routines around memcg's LRU is called by global LRU's
250 list management functions under zone->lru_lock(). 250 list management functions under zone->lru_lock().
@@ -337,7 +337,7 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
337 race and lock dependency with other cgroup subsystems. 337 race and lock dependency with other cgroup subsystems.
338 338
339 example) 339 example)
340 # mount -t cgroup none /cgroup -t cpuset,memory,cpu,devices 340 # mount -t cgroup none /cgroup -o cpuset,memory,cpu,devices
341 341
342 and do task move, mkdir, rmdir etc...under this. 342 and do task move, mkdir, rmdir etc...under this.
343 343
@@ -348,7 +348,7 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
348 348
349 For example, test like following is good. 349 For example, test like following is good.
350 (Shell-A) 350 (Shell-A)
351 # mount -t cgroup none /cgroup -t memory 351 # mount -t cgroup none /cgroup -o memory
352 # mkdir /cgroup/test 352 # mkdir /cgroup/test
353 # echo 40M > /cgroup/test/memory.limit_in_bytes 353 # echo 40M > /cgroup/test/memory.limit_in_bytes
354 # echo 0 > /cgroup/test/tasks 354 # echo 0 > /cgroup/test/tasks
@@ -378,3 +378,42 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
378 #echo 50M > memory.limit_in_bytes 378 #echo 50M > memory.limit_in_bytes
379 #echo 50M > memory.memsw.limit_in_bytes 379 #echo 50M > memory.memsw.limit_in_bytes
380 run 51M of malloc 380 run 51M of malloc
381
382 9.9 Move charges at task migration
383 Charges associated with a task can be moved along with task migration.
384
385 (Shell-A)
386 #mkdir /cgroup/A
387 #echo $$ >/cgroup/A/tasks
388 run some programs which uses some amount of memory in /cgroup/A.
389
390 (Shell-B)
391 #mkdir /cgroup/B
392 #echo 1 >/cgroup/B/memory.move_charge_at_immigrate
393 #echo "pid of the program running in group A" >/cgroup/B/tasks
394
395 You can see charges have been moved by reading *.usage_in_bytes or
396 memory.stat of both A and B.
397 See 8.2 of Documentation/cgroups/memory.txt to see what value should be
398 written to move_charge_at_immigrate.
399
400 9.10 Memory thresholds
401 Memory controler implements memory thresholds using cgroups notification
402 API. You can use Documentation/cgroups/cgroup_event_listener.c to test
403 it.
404
405 (Shell-A) Create cgroup and run event listener
406 # mkdir /cgroup/A
407 # ./cgroup_event_listener /cgroup/A/memory.usage_in_bytes 5M
408
409 (Shell-B) Add task to cgroup and try to allocate and free memory
410 # echo $$ >/cgroup/A/tasks
411 # a="$(dd if=/dev/zero bs=1M count=10)"
412 # a=
413
414 You will see message from cgroup_event_listener every time you cross
415 the thresholds.
416
417 Use /cgroup/A/memory.memsw.usage_in_bytes to test memsw thresholds.
418
419 It's good idea to test root cgroup as well.