* [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.
@ 2011-10-17 18:57 Rakib Mullick
2011-10-17 19:35 ` David Rientjes
0 siblings, 1 reply; 5+ messages in thread
From: Rakib Mullick @ 2011-10-17 18:57 UTC (permalink / raw)
To: linux-kernel; +Cc: akpm, Dmitry Torokhov
While doing allocation statistics in vmballoon_reserve_page function, alloc and sleep_alloc has been incremented even if allocation fails. But, b->stats.alloc and b->stats.sleep_alloc supposed to increment only when they succeed. This patch makes sure that, alloc and sleep_alloc gets incremented when page allocation succeeds.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
---
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 053d36c..d2c25c9 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -414,11 +414,6 @@ static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
bool locked = false;
do {
- if (!can_sleep)
- STATS_INC(b->stats.alloc);
- else
- STATS_INC(b->stats.sleep_alloc);
-
flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
page = alloc_page(flags);
if (!page) {
@@ -427,6 +422,11 @@ static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
else
STATS_INC(b->stats.sleep_alloc_fail);
return -ENOMEM;
+ } else {
+ if (!can_sleep)
+ STATS_INC(b->stats.alloc);
+ else
+ STATS_INC(b->stats.sleep_alloc);
}
/* inform monitor */
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.
2011-10-17 18:57 [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds Rakib Mullick
@ 2011-10-17 19:35 ` David Rientjes
2011-10-17 19:45 ` Dmitry Torokhov
0 siblings, 1 reply; 5+ messages in thread
From: David Rientjes @ 2011-10-17 19:35 UTC (permalink / raw)
To: Rakib Mullick; +Cc: linux-kernel, akpm, Dmitry Torokhov
On Tue, 18 Oct 2011, Rakib Mullick wrote:
> While doing allocation statistics in vmballoon_reserve_page function,
> alloc and sleep_alloc has been incremented even if allocation fails.
> But,
> b->stats.alloc and b->stats.sleep_alloc supposed to increment only when
> they succeed. This patch makes sure that, alloc and sleep_alloc gets
> incremented when page allocation succeeds.
>
Dmitry could say for sure, but this seems to actually change the
semantics. If the allocations fail, it increments alloc_fail and
sleep_alloc_fail accordingly so you could easily see 10 alloc and 5
alloc_fail. With your patch, it would be 5 alloc and 5 alloc_fail.
I don't know which one is best, but I would opt to stay with the semantics
that alloc and sleep_alloc have already had rather than changing them.
> Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
> ---
>
> diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
> index 053d36c..d2c25c9 100644
> --- a/drivers/misc/vmw_balloon.c
> +++ b/drivers/misc/vmw_balloon.c
> @@ -414,11 +414,6 @@ static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
> bool locked = false;
>
> do {
> - if (!can_sleep)
> - STATS_INC(b->stats.alloc);
> - else
> - STATS_INC(b->stats.sleep_alloc);
> -
> flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
> page = alloc_page(flags);
> if (!page) {
> @@ -427,6 +422,11 @@ static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
> else
> STATS_INC(b->stats.sleep_alloc_fail);
> return -ENOMEM;
> + } else {
> + if (!can_sleep)
> + STATS_INC(b->stats.alloc);
> + else
> + STATS_INC(b->stats.sleep_alloc);
> }
>
> /* inform monitor */
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.
2011-10-17 19:35 ` David Rientjes
@ 2011-10-17 19:45 ` Dmitry Torokhov
2011-10-17 20:17 ` Rakib Mullick
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry Torokhov @ 2011-10-17 19:45 UTC (permalink / raw)
To: David Rientjes; +Cc: Rakib Mullick, linux-kernel, akpm
On Monday, October 17, 2011 12:35:34 PM David Rientjes wrote:
> On Tue, 18 Oct 2011, Rakib Mullick wrote:
> > While doing allocation statistics in vmballoon_reserve_page function,
> >
> > alloc and sleep_alloc has been incremented even if allocation fails.
> > But,
> > b->stats.alloc and b->stats.sleep_alloc supposed to increment only
> > when they succeed. This patch makes sure that, alloc and sleep_alloc
> > gets incremented when page allocation succeeds.
>
> Dmitry could say for sure, but this seems to actually change the
> semantics. If the allocations fail, it increments alloc_fail and
> sleep_alloc_fail accordingly so you could easily see 10 alloc and 5
> alloc_fail. With your patch, it would be 5 alloc and 5 alloc_fail.
>
> I don't know which one is best, but I would opt to stay with the
> semantics that alloc and sleep_alloc have already had rather than
> changing them.
Right, b->stats.alloc and b->stats.sleep_alloc show number of allocation
attempts and alloc_fail and sleep_alloc_fail show how many of these
attempts failed. This behavior matches behavior of the driver we have
been shipping out of the tree for many years and I would prefer to keep
it as is.
Thanks,
Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.
2011-10-17 19:45 ` Dmitry Torokhov
@ 2011-10-17 20:17 ` Rakib Mullick
2011-10-17 20:25 ` Dmitry Torokhov
0 siblings, 1 reply; 5+ messages in thread
From: Rakib Mullick @ 2011-10-17 20:17 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: David Rientjes, linux-kernel, akpm
On Tue, Oct 18, 2011 at 1:45 AM, Dmitry Torokhov <dtor@vmware.com> wrote:
> On Monday, October 17, 2011 12:35:34 PM David Rientjes wrote:
>> On Tue, 18 Oct 2011, Rakib Mullick wrote:
>> > While doing allocation statistics in vmballoon_reserve_page function,
>> >
>> > alloc and sleep_alloc has been incremented even if allocation fails.
>> > But,
>> > b->stats.alloc and b->stats.sleep_alloc supposed to increment only
>> > when they succeed. This patch makes sure that, alloc and sleep_alloc
>> > gets incremented when page allocation succeeds.
>>
>> Dmitry could say for sure, but this seems to actually change the
>> semantics. If the allocations fail, it increments alloc_fail and
>> sleep_alloc_fail accordingly so you could easily see 10 alloc and 5
>> alloc_fail. With your patch, it would be 5 alloc and 5 alloc_fail.
>>
>> I don't know which one is best, but I would opt to stay with the
>> semantics that alloc and sleep_alloc have already had rather than
>> changing them.
>
> Right, b->stats.alloc and b->stats.sleep_alloc show number of allocation
> attempts and alloc_fail and sleep_alloc_fail show how many of these
> attempts failed. This behavior matches behavior of the driver we have
> been shipping out of the tree for many years and I would prefer to keep
> it as is.
>
Then why b->stats.alloc and b->stats.sleep_alloc are not renamed as
b->stats.alloc_attempted and b->stats.sleep_alloc_attempted
respectively. Current naming is confusing, anyone looking at the alloc
and sleep_alloc stat would easily think that, if 10 alloc and 5
alloc_fail then 10 has been allocated and 5 times has been allocation
fails. Isn't it?
Thanks,
Rakib
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.
2011-10-17 20:17 ` Rakib Mullick
@ 2011-10-17 20:25 ` Dmitry Torokhov
0 siblings, 0 replies; 5+ messages in thread
From: Dmitry Torokhov @ 2011-10-17 20:25 UTC (permalink / raw)
To: Rakib Mullick; +Cc: David Rientjes, linux-kernel, akpm
On Monday, October 17, 2011 01:17:02 PM Rakib Mullick wrote:
> On Tue, Oct 18, 2011 at 1:45 AM, Dmitry Torokhov <dtor@vmware.com> wrote:
> > On Monday, October 17, 2011 12:35:34 PM David Rientjes wrote:
> >> On Tue, 18 Oct 2011, Rakib Mullick wrote:
> >> > While doing allocation statistics in vmballoon_reserve_page
> >> > function,
> >> >
> >> > alloc and sleep_alloc has been incremented even if allocation
> >> > fails. But,
> >> > b->stats.alloc and b->stats.sleep_alloc supposed to increment only
> >> > when they succeed. This patch makes sure that, alloc and
> >> > sleep_alloc gets incremented when page allocation succeeds.
> >>
> >> Dmitry could say for sure, but this seems to actually change the
> >> semantics. If the allocations fail, it increments alloc_fail and
> >> sleep_alloc_fail accordingly so you could easily see 10 alloc and 5
> >> alloc_fail. With your patch, it would be 5 alloc and 5 alloc_fail.
> >>
> >> I don't know which one is best, but I would opt to stay with the
> >> semantics that alloc and sleep_alloc have already had rather than
> >> changing them.
> >
> > Right, b->stats.alloc and b->stats.sleep_alloc show number of
> > allocation attempts and alloc_fail and sleep_alloc_fail show how many
> > of these attempts failed. This behavior matches behavior of the
> > driver we have been shipping out of the tree for many years and I
> > would prefer to keep it as is.
>
> Then why b->stats.alloc and b->stats.sleep_alloc are not renamed as
> b->stats.alloc_attempted and b->stats.sleep_alloc_attempted
> respectively. Current naming is confusing, anyone looking at the alloc
> and sleep_alloc stat would easily think that, if 10 alloc and 5
> alloc_fail then 10 has been allocated and 5 times has been allocation
> fails. Isn't it?
I'd give you this point if they were named alloc_succeeded and
sleep_alloc_succeeded... but they are not.
Thanks,
Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread
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2011-10-17 18:57 [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds Rakib Mullick
2011-10-17 19:35 ` David Rientjes
2011-10-17 19:45 ` Dmitry Torokhov
2011-10-17 20:17 ` Rakib Mullick
2011-10-17 20:25 ` Dmitry Torokhov
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