YAMAMOTO Takashi wrote:
> hi,
>
> i implemented background reclamation for your memory controller and
> did a few benchmarks with and without it. any comments?
>
> YAMAMOTO Takashi
>
>
> -----
> "time make -j4 bzImage" in a cgroup with 64MB limit:
>
> without patch:
> real 22m22.389s
> user 13m35.163s
> sys 6m12.283s
>
> memory.failcnt after a run: 106647
>
> with patch:
> real 19m25.860s
> user 14m10.549s
> sys 6m13.831s
>
> memory.failcnt after a run: 35366
>
> "for x in 1 2 3;do time dd if=/dev/zero bs=1M count=300|tail;done"
> in a cgroup with 16MB limit:
>
> without patch:
> 300+0 records in
> 300+0 records out
> 314572800 bytes (315 MB) copied, 19.0058 seconds, 16.6 MB/s
> u 0.00s s 0.67s e 19.01s maj 90 min 2021 in 0 out 0
> u 0.48s s 7.22s e 93.13s maj 20475 min 210903 in 0 out 0
> 300+0 records in
> 300+0 records out
> 314572800 bytes (315 MB) copied, 14.8394 seconds, 21.2 MB/s
> u 0.00s s 0.63s e 14.84s maj 53 min 1392 in 0 out 0
> u 0.48s s 7.00s e 94.39s maj 20125 min 211145 in 0 out 0
> 300+0 records in
> 300+0 records out
> 314572800 bytes (315 MB) copied, 14.0635 seconds, 22.4 MB/s
> u 0.01s s 0.59s e 14.07s maj 50 min 1385 in 0 out 0
> u 0.57s s 6.93s e 91.54s maj 20359 min 210911 in 0 out 0
>
> memory.failcnt after a run: 8804
>
> with patch:
> 300+0 records in
> 300+0 records out
> 314572800 bytes (315 MB) copied, 5.94875 seconds, 52.9 MB/s
> u 0.00s s 0.67s e 5.95s maj 206 min 5393 in 0 out 0
> u 0.45s s 6.63s e 46.07s maj 21350 min 210252 in 0 out 0
> 300+0 records in
> 300+0 records out
> 314572800 bytes (315 MB) copied, 8.16441 seconds, 38.5 MB/s
> u 0.00s s 0.60s e 8.17s maj 240 min 4614 in 0 out 0
> u 0.45s s 6.56s e 54.56s maj 22298 min 209255 in 0 out 0
> 300+0 records in
> 300+0 records out
> 314572800 bytes (315 MB) copied, 4.60967 seconds, 68.2 MB/s
> u 0.00s s 0.60s e 4.64s maj 196 min 4733 in 0 out 0
> u 0.46s s 6.53s e 49.28s maj 22223 min 209384 in 0 out 0
>
> memory.failcnt after a run: 1589
Looks quite nice!
> -----
>
>
> --- linux-2.6.23-rc8-mm2-cgkswapd/mm/memcontrol.c.BACKUP 2007-10-01
> 17:19:57.000000000 +0900
> +++ linux-2.6.23-rc8-mm2-cgkswapd/mm/memcontrol.c 2007-10-22
> 13:46:01.000000000 +0900
> @@ -27,6 +27,7 @@
> #include <linux/rcupdate.h>
> #include <linux/swap.h>
> #include <linux/spinlock.h>
> +#include <linux/workqueue.h>
> #include <linux/fs.h>
>
> #include <asm/uaccess.h>
> @@ -63,6 +64,8 @@ struct mem_cgroup {
> */
> spinlock_t lru_lock;
> unsigned long control_type; /* control RSS or RSS+Pagecache */
> +
> + struct work_struct reclaim_work;
> };
>
> /*
> @@ -95,6 +98,9 @@ enum {
>
> static struct mem_cgroup init_mem_cgroup;
>
> +static DEFINE_MUTEX(mem_cgroup_workqueue_init_lock);
> +static struct workqueue_struct *mem_cgroup_workqueue;
> +
> static inline
> struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
> {
> @@ -250,6 +256,69 @@ unsigned long mem_cgroup_isolate_pages(u
> return nr_taken;
> }
>
> +static int
> +mem_cgroup_need_reclaim(struct mem_cgroup *mem)
> +{
> + struct res_counter * const cnt = &mem->res;
> + int doreclaim;
> + unsigned long flags;
> +
> + /* XXX should be in res_counter */
> + /* XXX should not hardcode a watermark */
We could add the following API to resource counters
res_counter_set_low_watermark
res_counter_set_high_watermark
res_counter_below_low_watermark
res_counter_above_high_watermark
and add
low_watermark
high_watermark
members to the resource group. We could push out data
upto the low watermark from the cgroup.
> + spin_lock_irqsave(&cnt->lock, flags);
> + doreclaim = cnt->usage > cnt->limit / 4 * 3;
> + spin_unlock_irqrestore(&cnt->lock, flags);
> +
> + return doreclaim;
> +}
> +
> +static void
> +mem_cgroup_schedule_reclaim_if_necessary(struct mem_cgroup *mem)
> +{
> +
> + if (mem_cgroup_workqueue == NULL) {
> + BUG_ON(mem->css.cgroup->parent != NULL);
> + return;
> + }
> +
> + if (work_pending(&mem->reclaim_work))
> + return;
> +
> + if (!mem_cgroup_need_reclaim(mem))
> + return;
> +
> + css_get(&mem->css); /* XXX need some thoughts wrt cgroup removal. */
> + /*
> + * XXX workqueue is not an ideal mechanism for our purpose.
> + * revisit later.
> + */
> + if (!queue_work(mem_cgroup_workqueue, &mem->reclaim_work))
> + css_put(&mem->css);
> +}
> +
> +static void
> +mem_cgroup_reclaim(struct work_struct *work)
> +{
> + struct mem_cgroup * const mem =
> + container_of(work, struct mem_cgroup, reclaim_work);
> + int batch_count = 128; /* XXX arbitrary */
> +
> + for (; batch_count > 0; batch_count--) {
> + if (!mem_cgroup_need_reclaim(mem))
> + break;
> + /*
> + * XXX try_to_free_foo is not a correct mechanism to
> + * use here. eg. ALLOCSTALL counter
> + * revisit later.
> + */
> + if (!try_to_free_mem_cgroup_pages(mem, GFP_KERNEL))
We could make try_to_free_mem_cgroup_pages, batch aware and pass that
in scan_control.
> + break;
> + }
> + if (batch_count == 0)
> + mem_cgroup_schedule_reclaim_if_necessary(mem);
> + css_put(&mem->css);
> +}
> +
> /*
> * Charge the memory controller for page usage.
> * Return
> @@ -311,6 +380,9 @@ int mem_cgroup_charge(struct page *page,
> */
> while (res_counter_charge(&mem->res, PAGE_SIZE)) {
> bool is_atomic = gfp_mask & GFP_ATOMIC;
> +
> + mem_cgroup_schedule_reclaim_if_necessary(mem);
> +
> /*
> * We cannot reclaim under GFP_ATOMIC, fail the charge
> */
> @@ -551,8 +623,18 @@ mem_cgroup_create(struct cgroup_subsys *
> if (unlikely((cont->parent) == NULL)) {
> mem = &init_mem_cgroup;
> init_mm.mem_cgroup = mem;
> - } else
> + } else {
> + /* XXX too late for the top-level cgroup */
> + if (mem_cgroup_workqueue == NULL) {
> + mutex_lock(&mem_cgroup_workqueue_init_lock);
> + if (mem_cgroup_workqueue == NULL) {
> + mem_cgroup_workqueue =
> + create_workqueue("mem_cgroup");
> + }
> + mutex_unlock(&mem_cgroup_workqueue_init_lock);
> + }
> mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL);
> + }
>
> if (mem == NULL)
> return NULL;
> @@ -562,6 +644,7 @@ mem_cgroup_create(struct cgroup_subsys *
> INIT_LIST_HEAD(&mem->inactive_list);
> spin_lock_init(&mem->lru_lock);
> mem->control_type = MEM_CGROUP_TYPE_ALL;
> + INIT_WORK(&mem->reclaim_work, mem_cgroup_reclaim);
> return &mem->css;
> }
>
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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