From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id C1CB0900086 for ; Mon, 18 Apr 2011 17:38:29 -0400 (EDT) Received: from hpaq1.eem.corp.google.com (hpaq1.eem.corp.google.com [172.25.149.1]) by smtp-out.google.com with ESMTP id p3ILcPb8015913 for ; Mon, 18 Apr 2011 14:38:25 -0700 Received: from qwf7 (qwf7.prod.google.com [10.241.194.71]) by hpaq1.eem.corp.google.com with ESMTP id p3ILcNEt021749 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Mon, 18 Apr 2011 14:38:23 -0700 Received: by qwf7 with SMTP id 7so2688866qwf.10 for ; Mon, 18 Apr 2011 14:38:22 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1302909815-4362-1-git-send-email-yinghan@google.com> <1302909815-4362-7-git-send-email-yinghan@google.com> Date: Mon, 18 Apr 2011 14:38:22 -0700 Message-ID: Subject: Re: [PATCH V5 06/10] Per-memcg background reclaim. From: Ying Han Content-Type: multipart/alternative; boundary=000e0cdfd082f7ed9604a138350d Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: KOSAKI Motohiro , Daisuke Nishimura , Balbir Singh , Tejun Heo , Pavel Emelyanov , KAMEZAWA Hiroyuki , Andrew Morton , Li Zefan , Mel Gorman , Christoph Lameter , Johannes Weiner , Rik van Riel , Hugh Dickins , Michal Hocko , Dave Hansen , Zhu Yanhai , linux-mm@kvack.org --000e0cdfd082f7ed9604a138350d Content-Type: text/plain; charset=ISO-8859-1 On Sun, Apr 17, 2011 at 8:51 PM, Minchan Kim wrote: > On Sat, Apr 16, 2011 at 8:23 AM, Ying Han wrote: > > This is the main loop of per-memcg background reclaim which is > implemented in > > function balance_mem_cgroup_pgdat(). > > > > The function performs a priority loop similar to global reclaim. During > each > > iteration it invokes balance_pgdat_node() for all nodes on the system, > which > > is another new function performs background reclaim per node. After > reclaiming > > each node, it checks mem_cgroup_watermark_ok() and breaks the priority > loop if > > it returns true. > > > > changelog v5..v4: > > 1. remove duplicate check on nodes_empty() > > 2. add logic to check if the per-memcg lru is empty on the zone. > > 3. make per-memcg kswapd to reclaim SWAP_CLUSTER_MAX per zone. It make > senses > > since it helps to balance the pressure across zones within the memcg. > > > > changelog v4..v3: > > 1. split the select_victim_node and zone_unreclaimable to a seperate > patches > > 2. remove the logic tries to do zone balancing. > > > > changelog v3..v2: > > 1. change mz->all_unreclaimable to be boolean. > > 2. define ZONE_RECLAIMABLE_RATE macro shared by zone and per-memcg > reclaim. > > 3. some more clean-up. > > > > changelog v2..v1: > > 1. move the per-memcg per-zone clear_unreclaimable into uncharge stage. > > 2. shared the kswapd_run/kswapd_stop for per-memcg and global background > > reclaim. > > 3. name the per-memcg memcg as "memcg-id" (css->id). And the global > kswapd > > keeps the same name. > > 4. fix a race on kswapd_stop while the per-memcg-per-zone info could be > accessed > > after freeing. > > 5. add the fairness in zonelist where memcg remember the last zone > reclaimed > > from. > > > > Signed-off-by: Ying Han > > --- > > mm/vmscan.c | 157 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 files changed, 157 insertions(+), 0 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 06036d2..39e6300 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -47,6 +47,8 @@ > > > > #include > > > > +#include > > + > > #include "internal.h" > > > > #define CREATE_TRACE_POINTS > > @@ -111,6 +113,8 @@ struct scan_control { > > * are scanned. > > */ > > nodemask_t *nodemask; > > + > > + int priority; > > }; > > > > #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) > > @@ -2631,11 +2635,164 @@ static void kswapd_try_to_sleep(struct kswapd > *kswapd_p, int order, > > finish_wait(wait_h, &wait); > > } > > > > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR > > +/* > > + * The function is used for per-memcg LRU. It scanns all the zones of > the > > + * node and returns the nr_scanned and nr_reclaimed. > > + */ > > +static void balance_pgdat_node(pg_data_t *pgdat, int order, > > + struct scan_control *sc) > > +{ > > + int i; > > + unsigned long total_scanned = 0; > > + struct mem_cgroup *mem_cont = sc->mem_cgroup; > > + int priority = sc->priority; > > + enum lru_list l; > > + > > + /* > > + * This dma->highmem order is consistant with global reclaim. > > + * We do this because the page allocator works in the opposite > > + * direction although memcg user pages are mostly allocated at > > + * highmem. > > + */ > > + for (i = 0; i < pgdat->nr_zones; i++) { > > + struct zone *zone = pgdat->node_zones + i; > > + unsigned long scan = 0; > > + > > + for_each_evictable_lru(l) > > + scan += mem_cgroup_zone_nr_pages(mem_cont, zone, > l); > > + > > + if (!populated_zone(zone) || !scan) > > + continue; > > Do we really need this double check? Isn't only _scan_ check enough? > yes. will change on next post. > And shouldn't we consider non-swap case? > good point. we don't need to count the anon lru in non-swap case. A new function will be added to count the memcg_zone_reclaimable per zone. > > > + > > + sc->nr_scanned = 0; > > + shrink_zone(priority, zone, sc); > > + total_scanned += sc->nr_scanned; > > + > > + /* > > + * If we've done a decent amount of scanning and > > + * the reclaim ratio is low, start doing writepage > > + * even in laptop mode > > + */ > > + if (total_scanned > SWAP_CLUSTER_MAX * 2 && > > + total_scanned > sc->nr_reclaimed + sc->nr_reclaimed / > 2) { > > + sc->may_writepage = 1; > > I don't want to add more random write any more although we don't have > a trouble of real memory shortage. > > Do you have any reason to reclaim memory urgently as writing dirty pages? > Maybe if we wait a little bit of time, flusher would write out the page. > We would like to reduce the writing dirty pages from page reclaim, especially from direct reclaim. AFAIK, the try_to_free_mem_cgroup_pages() still need to write dirty pages when there is a need. removing this from the per-memcg kswap will only add more pressure to the per-memcg direct reclaim, which seems to be worse. (stack overflow as one example which we would like to get rid of) > > > + } > > + } > > + > > + sc->nr_scanned = total_scanned; > > + return; > > unnecessary return. > > removed. > > +} > > + > > +/* > > + * Per cgroup background reclaim. > > + * TODO: Take off the order since memcg always do order 0 > > + */ > > +static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup > *mem_cont, > > + int order) > > +{ > > + int i, nid; > > + int start_node; > > + int priority; > > + bool wmark_ok; > > + int loop; > > + pg_data_t *pgdat; > > + nodemask_t do_nodes; > > + unsigned long total_scanned; > > + struct scan_control sc = { > > + .gfp_mask = GFP_KERNEL, > > + .may_unmap = 1, > > + .may_swap = 1, > > + .nr_to_reclaim = SWAP_CLUSTER_MAX, > > + .swappiness = vm_swappiness, > > + .order = order, > > + .mem_cgroup = mem_cont, > > + }; > > + > > +loop_again: > > + do_nodes = NODE_MASK_NONE; > > + sc.may_writepage = !laptop_mode; > > I think it depends on urgency(ie, priority, reclaim > ratio(#reclaim/#scanning) or something), not laptop_mode in case of > memcg. > As I said earlier,it wold be better to avoid random write. > I agree that we would like to avoid it. but not sure if we should remove it here, since it add more pressure to the direct reclaim case. > > > + sc.nr_reclaimed = 0; > > + total_scanned = 0; > > + > > + for (priority = DEF_PRIORITY; priority >= 0; priority--) { > > + sc.priority = priority; > > + wmark_ok = false; > > + loop = 0; > > + > > + /* The swap token gets in the way of swapout... */ > > + if (!priority) > > + disable_swap_token(); > > + > > + if (priority == DEF_PRIORITY) > > + do_nodes = node_states[N_ONLINE]; > > + > > + while (1) { > > + nid = mem_cgroup_select_victim_node(mem_cont, > > + &do_nodes); > > + > > + /* Indicate we have cycled the nodelist once > > Fix comment style. > Fixed. > > > + * TODO: we might add MAX_RECLAIM_LOOP for > preventing > > + * kswapd burning cpu cycles. > > + */ > > + if (loop == 0) { > > + start_node = nid; > > + loop++; > > + } else if (nid == start_node) > > + break; > > + > > + pgdat = NODE_DATA(nid); > > + balance_pgdat_node(pgdat, order, &sc); > > + total_scanned += sc.nr_scanned; > > + > > + /* Set the node which has at least > > Fix comment style. > > Fixed. > > + * one reclaimable zone > > + */ > > + for (i = pgdat->nr_zones - 1; i >= 0; i--) { > > + struct zone *zone = pgdat->node_zones + > i; > > + > > + if (!populated_zone(zone)) > > + continue; > > + } > > I can't understand your comment and logic. > The comment mentioned reclaimable zone but the logic checks just > populated_zone. What's meaning? > I will move the comment to another patch which adds the zone unreclaimable. --Ying > > > + if (i < 0) > > + node_clear(nid, do_nodes); > > + > > + if (mem_cgroup_watermark_ok(mem_cont, > > + > CHARGE_WMARK_HIGH)) { > > + wmark_ok = true; > > + goto out; > > + } > > + > > + if (nodes_empty(do_nodes)) { > > + wmark_ok = true; > > + goto out; > > + } > > + } > > + > > + if (total_scanned && priority < DEF_PRIORITY - 2) > > + congestion_wait(WRITE, HZ/10); > > + > > + if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) > > + break; > > + } > > +out: > > + if (!wmark_ok) { > > + cond_resched(); > > + > > + try_to_freeze(); > > + > > + goto loop_again; > > + } > > + > > + return sc.nr_reclaimed; > > +} > > +#else > > static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup > *mem_cont, > > int order) > > { > > return 0; > > } > > +#endif > > > > /* > > * The background pageout daemon, started as a kernel thread > > -- > > 1.7.3.1 > > > > > > > > -- > Kind regards, > Minchan Kim > --000e0cdfd082f7ed9604a138350d Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

On Sun, Apr 17, 2011 at 8:51 PM, Minchan= Kim <minchan= .kim@gmail.com> wrote:
On Sat, Apr 16, 2011 at 8:23 AM, Ying Han= <yinghan@google.com> wrote= :
> This is the main loop of per-memcg background reclaim which is impleme= nted in
> function balance_mem_cgroup_pgdat().
>
> The function performs a priority loop similar to global reclaim. Durin= g each
> iteration it invokes balance_pgdat_node() for all nodes on the system,= which
> is another new function performs background reclaim per node. After re= claiming
> each node, it checks mem_cgroup_watermark_ok() and breaks the priority= loop if
> it returns true.
>
> changelog v5..v4:
> 1. remove duplicate check on nodes_empty()
> 2. add logic to check if the per-memcg lru is empty on the zone.
> 3. make per-memcg kswapd to reclaim SWAP_CLUSTER_MAX per zone. It make= senses
> since it helps to balance the pressure across zones within the memcg.<= br> >
> changelog v4..v3:
> 1. split the select_victim_node and zone_unreclaimable to a seperate p= atches
> 2. remove the logic tries to do zone balancing.
>
> changelog v3..v2:
> 1. change mz->all_unreclaimable to be boolean.
> 2. define ZONE_RECLAIMABLE_RATE macro shared by zone and per-memcg rec= laim.
> 3. some more clean-up.
>
> changelog v2..v1:
> 1. move the per-memcg per-zone clear_unreclaimable into uncharge stage= .
> 2. shared the kswapd_run/kswapd_stop for per-memcg and global backgrou= nd
> reclaim.
> 3. name the per-memcg memcg as "memcg-id" (css->id). And = the global kswapd
> keeps the same name.
> 4. fix a race on kswapd_stop while the per-memcg-per-zone info could b= e accessed
> after freeing.
> 5. add the fairness in zonelist where memcg remember the last zone rec= laimed
> from.
>
> Signed-off-by: Ying Han <ying= han@google.com>
> ---
> =A0mm/vmscan.c | =A0157 ++++++++++++++++++++++++++++++++++++++++++++++= +++++++++++++
> =A01 files changed, 157 insertions(+), 0 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 06036d2..39e6300 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -47,6 +47,8 @@
>
> =A0#include <linux/swapops.h>
>
> +#include <linux/res_counter.h>
> +
> =A0#include "internal.h"
>
> =A0#define CREATE_TRACE_POINTS
> @@ -111,6 +113,8 @@ struct scan_control {
> =A0 =A0 =A0 =A0 * are scanned.
> =A0 =A0 =A0 =A0 */
> =A0 =A0 =A0 =A0nodemask_t =A0 =A0 =A0*nodemask;
> +
> + =A0 =A0 =A0 int priority;
> =A0};
>
> =A0#define lru_to_page(_head) (list_entry((_head)->prev, struct pag= e, lru))
> @@ -2631,11 +2635,164 @@ static void kswapd_try_to_sleep(struct kswapd= *kswapd_p, int order,
> =A0 =A0 =A0 =A0finish_wait(wait_h, &wait);
> =A0}
>
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR
> +/*
> + * The function is used for per-memcg LRU. It scanns all the zones of= the
> + * node and returns the nr_scanned and nr_reclaimed.
> + */
> +static void balance_pgdat_node(pg_data_t *pgdat, int order,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 struct scan_control *sc)
> +{
> + =A0 =A0 =A0 int i;
> + =A0 =A0 =A0 unsigned long total_scanned =3D 0;
> + =A0 =A0 =A0 struct mem_cgroup *mem_cont =3D sc->mem_cgroup;
> + =A0 =A0 =A0 int priority =3D sc->priority;
> + =A0 =A0 =A0 enum lru_list l;
> +
> + =A0 =A0 =A0 /*
> + =A0 =A0 =A0 =A0* This dma->highmem order is consistant with globa= l reclaim.
> + =A0 =A0 =A0 =A0* We do this because the page allocator works in the = opposite
> + =A0 =A0 =A0 =A0* direction although memcg user pages are mostly allo= cated at
> + =A0 =A0 =A0 =A0* highmem.
> + =A0 =A0 =A0 =A0*/
> + =A0 =A0 =A0 for (i =3D 0; i < pgdat->nr_zones; i++) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct zone *zone =3D pgdat->node_zon= es + i;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 unsigned long scan =3D 0;
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 for_each_evictable_lru(l)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 scan +=3D mem_cgroup_zon= e_nr_pages(mem_cont, zone, l);
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (!populated_zone(zone) || !scan)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 continue;

Do we really need this double check?=A0
Isn't only _scan_ check enough?

yes= . will change on next post.
=A0
And shouldn't we consider non-swap case?

good point. we don't need to count the anon lru in non-swap case.= A new function will be added to count the memcg_zone_reclaimable per zone.=
=A0

> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 sc->nr_scanned =3D 0;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 shrink_zone(priority, = zone, sc);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 total_scanned +=3D sc->nr_scanned; > +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 /*
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* If we've done a decent amount o= f scanning and
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* the reclaim ratio is low, start doi= ng writepage
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* even in laptop mode
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*/
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (total_scanned > SWAP_CLUSTER_MAX = * 2 &&
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 total_scanned > sc->nr_rec= laimed + sc->nr_reclaimed / 2) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 sc->may_writepage =3D= 1;

I don't want to add more random write any more although we don= 9;t have
a trouble of real memory shortage.
=A0
Do you have any reason to reclaim memory urgently as writing dirty pages? Maybe if we wait a little bit of time, flusher would write out the page.

We would like to reduce the writing dirty= pages from page reclaim, especially from direct reclaim. AFAIK, the=A0try_= to_free_mem_cgroup_pages() still need to write dirty pages when there is a = need. removing this from the per-memcg kswap will only add more pressure to= the per-memcg direct reclaim, which seems to be worse. (stack overflow as = one example which we would like to get rid of)
=A0

> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> + =A0 =A0 =A0 }
> +
> + =A0 =A0 =A0 sc->nr_scanned =3D total_scanned;
> + =A0 =A0 =A0 return;

unnecessary return.

removed.
=A0
<= blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px= #ccc solid;padding-left:1ex;">
> +}
> +
> +/*
> + * Per cgroup background reclaim.
> + * TODO: Take off the order since memcg always do order 0
> + */
> +static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup *mem_= cont,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 int order)
> +{
> + =A0 =A0 =A0 int i, nid;
> + =A0 =A0 =A0 int start_node;
> + =A0 =A0 =A0 int priority;
> + =A0 =A0 =A0 bool wmark_ok;
> + =A0 =A0 =A0 int loop;
> + =A0 =A0 =A0 pg_data_t *pgdat;
> + =A0 =A0 =A0 nodemask_t do_nodes;
> + =A0 =A0 =A0 unsigned long total_scanned;
> + =A0 =A0 =A0 struct scan_control sc =3D {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .gfp_mask =3D GFP_KERNEL,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .may_unmap =3D 1,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .may_swap =3D 1,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .nr_to_reclaim =3D SWAP_CLUSTER_MAX,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .swappiness =3D vm_swappiness,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .order =3D order,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .mem_cgroup =3D mem_cont,
> + =A0 =A0 =A0 };
> +
> +loop_again:
> + =A0 =A0 =A0 do_nodes =3D NODE_MASK_NONE;
> + =A0 =A0 =A0 sc.may_writepage =3D !laptop_mode;

I think it depends on urgency(ie, priority, reclaim
ratio(#reclaim/#scanning) or something), not laptop_mode in case of
memcg.
As I said earlier,it wold be better to avoid random write.
=

I agree that we would like to avoid it. but not sure if= we should remove it here, since it add more pressure to the direct reclaim= case.=A0

> + =A0 =A0 =A0 sc.nr_reclaimed =3D 0;
> + =A0 =A0 =A0 total_scanned =3D 0;
> +
> + =A0 =A0 =A0 for (priority =3D DEF_PRIORITY; priority >=3D 0; prio= rity--) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 sc.priority =3D priority;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 wmark_ok =3D false;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 loop =3D 0;
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* The swap token gets in the way of swa= pout... */
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (!priority)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 disable_swap_token(); > +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (priority =3D=3D DEF_PRIORITY)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 do_nodes =3D node_states= [N_ONLINE];
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 while (1) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 nid =3D mem_cgroup_selec= t_victim_node(mem_cont,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 &do_nodes);
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* Indicate we have cycl= ed the nodelist once

Fix comment style.

Fixed.=A0

> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* TODO: we might add = MAX_RECLAIM_LOOP for preventing
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* k= swapd burning cpu cycles.
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*/
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (loop =3D=3D 0) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 start_no= de =3D nid;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 loop++;<= br> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 } else if (nid =3D=3D st= art_node)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 break; > +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 pgdat =3D NODE_DATA(nid)= ;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 balance_pgdat_node(pgdat= , order, &sc);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 total_scanned +=3D sc.nr= _scanned;
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* Set the node which ha= s at least

Fix comment style.

Fixed.
=A0
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* one reclaimable zon= e
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*/<= br> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 for (i =3D pgdat->nr_= zones - 1; i >=3D 0; i--) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct z= one *zone =3D pgdat->node_zones + i;
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (!pop= ulated_zone(zone))
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 continue;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }

I can't understand your comment and logic.
The comment mentioned reclaimable zone but the logic checks just
populated_zone. What's meaning?

I w= ill move the comment to another patch which adds the zone unreclaimable.

--Ying=A0

> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (i < 0)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 node_clear(nid, do_nodes);
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (mem_cgroup_watermark= _ok(mem_cont,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 CHARGE_WMARK_HIGH)) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 wmark_ok= =3D true;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto out= ;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (nodes_empty(do_nodes= )) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 wmark_ok= =3D true;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto out= ;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (total_scanned && priority &l= t; DEF_PRIORITY - 2)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 congestion_wait(WRITE, H= Z/10);
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (sc.nr_reclaimed >=3D SWAP_CLUSTER= _MAX)
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 break;
> + =A0 =A0 =A0 }
> +out:
> + =A0 =A0 =A0 if (!wmark_ok) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 cond_resched();
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 try_to_freeze();
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto loop_again;
> + =A0 =A0 =A0 }
> +
> + =A0 =A0 =A0 return sc.nr_reclaimed;
> +}
> +#else
> =A0static unsigned long balance_mem_cgroup_pgdat(struct mem_cgroup *me= m_cont,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0int order)
> =A0{
> =A0 =A0 =A0 =A0return 0;
> =A0}
> +#endif
>
> =A0/*
> =A0* The background pageout daemon, started as a kernel thread
> --
> 1.7.3.1
>
>



--
Kind regards,
Minchan Kim

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