2012-11-09 02:20:54

by Shan Wei

Subject: [PATCH v3 2/9] net: rds: use this_cpu_ptr per-cpu helper

From: Shan Wei <[email protected]>

Signed-off-by: Shan Wei <[email protected]>
Reviewed-by: Christoph Lameter <[email protected]>
---
no changes vs v2.
---
net/rds/ib_recv.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 8d19491..a4a5064 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -423,7 +423,7 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,

local_irq_save(flags);

- chp = per_cpu_ptr(cache->percpu, smp_processor_id());
+ chp = this_cpu_ptr(cache->percpu);
if (!chp->first)
INIT_LIST_HEAD(new_item);
else /* put on front */
--
1.7.1

2012-11-09 20:09:48

by Christoph Lameter (Ampere)

Subject: Re: [PATCH v3 2/9] net: rds: use this_cpu_ptr per-cpu helper

On Fri, 9 Nov 2012, Shan Wei wrote:

> net/rds/ib_recv.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
> index 8d19491..a4a5064 100644
> --- a/net/rds/ib_recv.c
> +++ b/net/rds/ib_recv.c
> @@ -423,7 +423,7 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,
>
> local_irq_save(flags);
>
> - chp = per_cpu_ptr(cache->percpu, smp_processor_id());
> + chp = this_cpu_ptr(cache->percpu);
> if (!chp->first)

if (!__this_cpu_read(cache-0>percpu->first))

?

2012-11-12 12:47:44

by Shan Wei

Subject: Re: [PATCH v3 2/9] net: rds: use this_cpu_ptr per-cpu helper

Christoph Lameter said, at 2012/11/10 4:09:
>> - chp = per_cpu_ptr(cache->percpu, smp_processor_id());
>> + chp = this_cpu_ptr(cache->percpu);
>> if (!chp->first)
>
> if (!__this_cpu_read(cache-0>percpu->first))
>
> ?

__percpu annotations in struct rds_ib_refill_cache is missing.

you mean that read/write fields of struct rds_ib_cache_head
using __this_cpu_* operation like following?
How about it?

diff --git a/net/rds/ib.h b/net/rds/ib.h
index 8d2b3d5..7280ab8 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -50,7 +50,7 @@ struct rds_ib_cache_head {
};

struct rds_ib_refill_cache {
- struct rds_ib_cache_head *percpu;
+ struct rds_ib_cache_head __percpu *percpu;
struct list_head *xfer;
struct list_head *ready;
};
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index 8d19491..8c5bc85 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -418,20 +418,21 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,
struct rds_ib_refill_cache *cache)
{
unsigned long flags;
- struct rds_ib_cache_head *chp;
struct list_head *old;
+ struct list_head __percpu *chpfirst;

local_irq_save(flags);

- chp = per_cpu_ptr(cache->percpu, smp_processor_id());
- if (!chp->first)
+ chpfirst = __this_cpu_read(cache->percpu->first);
+ if (!chpfirst)
INIT_LIST_HEAD(new_item);
else /* put on front */
- list_add_tail(new_item, chp->first);
- chp->first = new_item;
- chp->count++;
+ list_add_tail(new_item, chpfirst);

- if (chp->count < RDS_IB_RECYCLE_BATCH_COUNT)
+ __this_cpu_write(chpfirst, new_item);
+ __this_cpu_inc(cache->percpu->count);
+
+ if (__this_cpu_read(cache->percpu->count) < RDS_IB_RECYCLE_BATCH_COUNT)
goto end;

/*
@@ -443,12 +444,13 @@ static void rds_ib_recv_cache_put(struct list_head *new_item,
do {
old = xchg(&cache->xfer, NULL);
if (old)
- list_splice_entire_tail(old, chp->first);
- old = cmpxchg(&cache->xfer, NULL, chp->first);
+ list_splice_entire_tail(old, chpfirst);
+ old = cmpxchg(&cache->xfer, NULL, chpfirst);
} while (old);

- chp->first = NULL;
- chp->count = 0;
+
+ __this_cpu_write(chpfirst, NULL);
+ __this_cpu_write(cache->percpu->count, 0);
end:
local_irq_restore(flags);
}

2012-11-12 23:31:17

by Christoph Lameter (Ampere)

Subject: Re: [PATCH v3 2/9] net: rds: use this_cpu_ptr per-cpu helper

On Mon, 12 Nov 2012, Shan Wei wrote:

> __percpu annotations in struct rds_ib_refill_cache is missing.
>
> you mean that read/write fields of struct rds_ib_cache_head
> using __this_cpu_* operation like following?
> How about it?
>
> diff --git a/net/rds/ib.h b/net/rds/ib.h
> index 8d2b3d5..7280ab8 100644
> --- a/net/rds/ib.h
> +++ b/net/rds/ib.h
> @@ -50,7 +50,7 @@ struct rds_ib_cache_head {
> };
>
> struct rds_ib_refill_cache {
> - struct rds_ib_cache_head *percpu;
> + struct rds_ib_cache_head __percpu *percpu;

That looks ok.