On Mon, 2014-06-23 at 12:19 +0100, Mel Gorman wrote:
> On Mon, Jun 23, 2014 at 01:14:54PM +0800, Chen Yucong wrote:
> > According to the commit 215ddd66 (mm: vmscan: only read new_classzone_idx from
> > pgdat when reclaiming successfully) and the commit d2ebd0f6b (kswapd: avoid
> > unnecessary rebalance after an unsuccessful balancing), we can use a boolean
> > variable for replace balanced_* variables, which makes the kswapd more clarify.
> >
> > Signed-off-by: Chen Yucong <slaoub@xxxxxxxxx>
>
> I think this is just churning code for the sake of it. It's not any
> easier to understand as a result of the modification and does not appear
> to be a preparation for a follow-on patch that addresses a bug.
>
Anyway, there are some palaces that still need to be cleaned in
`kswapd'.
thx!
cyc
Subject: [PATCH] mm:kswapd: clean up the kswapd
The type of variables(order, new_order, and balanced_order) has some
flaws.
According to the `order' argument for kswapd_try_to_sleep() and
balance_pgdat(),
they should be defined as `int' rather than `unsigned long' or
`unsigned'.
This patch also does minimal cleanup, which makes the kswapd more
clarify.
Signed-off-by: Chen Yucong <slaoub@xxxxxxxxx>
---
mm/vmscan.c | 33 ++++++++++++++++++---------------
1 file changed, 18 insertions(+), 15 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a8ffe4e..1b2576d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3332,8 +3332,8 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat,
int order, int classzone_idx)
*/
static int kswapd(void *p)
{
- unsigned long order, new_order;
- unsigned balanced_order;
+ int order, new_order;
+ int balanced_order;
int classzone_idx, new_classzone_idx;
int balanced_classzone_idx;
pg_data_t *pgdat = (pg_data_t*)p;
@@ -3371,34 +3371,37 @@ static int kswapd(void *p)
balanced_classzone_idx = classzone_idx;
for ( ; ; ) {
bool ret;
+ bool sleep = true;
/*
* If the last balance_pgdat was unsuccessful it's unlikely a
* new request of a similar or harder type will succeed soon
* so consider going to sleep on the basis we reclaimed at
*/
- if (balanced_classzone_idx >= new_classzone_idx &&
- balanced_order == new_order) {
+ if (balanced_classzone_idx >= classzone_idx &&
+ balanced_order == order) {
new_order = pgdat->kswapd_max_order;
new_classzone_idx = pgdat->classzone_idx;
- pgdat->kswapd_max_order = 0;
+ pgdat->kswapd_max_order = 0;
pgdat->classzone_idx = pgdat->nr_zones - 1;
+
+ if (order < new_order ||
+ classzone_idx > new_classzone_idx) {
+ /*
+ * Don't sleep if someone wants a larger 'order'
+ * allocation or has tighter zone constraints
+ */
+ order = new_order;
+ classzone_idx = new_classzone_idx;
+ sleep = false;
+ }
}
- if (order < new_order || classzone_idx > new_classzone_idx) {
- /*
- * Don't sleep if someone wants a larger 'order'
- * allocation or has tigher zone constraints
- */
- order = new_order;
- classzone_idx = new_classzone_idx;
- } else {
+ if (sleep) {
kswapd_try_to_sleep(pgdat, balanced_order,
balanced_classzone_idx);
order = pgdat->kswapd_max_order;
classzone_idx = pgdat->classzone_idx;
- new_order = order;
- new_classzone_idx = classzone_idx;
pgdat->kswapd_max_order = 0;
pgdat->classzone_idx = pgdat->nr_zones - 1;
}
--
1.7.10.4
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