* [PATCH V2] blk-mq: balance mapping between present CPUs and queues
@ 2019-07-25 9:41 Ming Lei
2019-07-25 9:50 ` Bob Liu
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Ming Lei @ 2019-07-25 9:41 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block, Ming Lei, Yi Zhang, Bob Liu
Spread queues among present CPUs first, then building mapping on other
non-present CPUs.
So we can minimize count of dead queues which are mapped by un-present
CPUs only. Then bad IO performance can be avoided by unbalanced mapping
between present CPUs and queues.
The similar policy has been applied on Managed IRQ affinity.
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Cc: Yi Zhang <yi.zhang@redhat.com>
Cc: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
V2:
- make sure that sequential mapping can be done
block/blk-mq-cpumap.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
index f945621a0e8f..0157f2b3485a 100644
--- a/block/blk-mq-cpumap.c
+++ b/block/blk-mq-cpumap.c
@@ -15,10 +15,10 @@
#include "blk.h"
#include "blk-mq.h"
-static int cpu_to_queue_index(struct blk_mq_queue_map *qmap,
- unsigned int nr_queues, const int cpu)
+static int queue_index(struct blk_mq_queue_map *qmap,
+ unsigned int nr_queues, const int q)
{
- return qmap->queue_offset + (cpu % nr_queues);
+ return qmap->queue_offset + (q % nr_queues);
}
static int get_first_sibling(unsigned int cpu)
@@ -36,21 +36,36 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
{
unsigned int *map = qmap->mq_map;
unsigned int nr_queues = qmap->nr_queues;
- unsigned int cpu, first_sibling;
+ unsigned int cpu, first_sibling, q = 0;
+
+ for_each_possible_cpu(cpu)
+ map[cpu] = -1;
+
+ /*
+ * Spread queues among present CPUs first for minimizing
+ * count of dead queues which are mapped by all un-present CPUs
+ */
+ for_each_present_cpu(cpu) {
+ if (q >= nr_queues)
+ break;
+ map[cpu] = queue_index(qmap, nr_queues, q++);
+ }
for_each_possible_cpu(cpu) {
+ if (map[cpu] != -1)
+ continue;
/*
* First do sequential mapping between CPUs and queues.
* In case we still have CPUs to map, and we have some number of
* threads per cores then map sibling threads to the same queue
* for performance optimizations.
*/
- if (cpu < nr_queues) {
- map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
+ if (q < nr_queues) {
+ map[cpu] = queue_index(qmap, nr_queues, q++);
} else {
first_sibling = get_first_sibling(cpu);
if (first_sibling == cpu)
- map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
+ map[cpu] = queue_index(qmap, nr_queues, q++);
else
map[cpu] = map[first_sibling];
}
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH V2] blk-mq: balance mapping between present CPUs and queues
2019-07-25 9:41 [PATCH V2] blk-mq: balance mapping between present CPUs and queues Ming Lei
@ 2019-07-25 9:50 ` Bob Liu
2019-08-05 0:57 ` Ming Lei
2019-08-05 3:43 ` Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Bob Liu @ 2019-07-25 9:50 UTC (permalink / raw)
To: Ming Lei, Jens Axboe; +Cc: linux-block, Yi Zhang
On 7/25/19 5:41 PM, Ming Lei wrote:
> Spread queues among present CPUs first, then building mapping on other
> non-present CPUs.
>
> So we can minimize count of dead queues which are mapped by un-present
> CPUs only. Then bad IO performance can be avoided by unbalanced mapping
> between present CPUs and queues.
>
> The similar policy has been applied on Managed IRQ affinity.
>
> Reported-by: Yi Zhang <yi.zhang@redhat.com>
> Cc: Yi Zhang <yi.zhang@redhat.com>
> Cc: Bob Liu <bob.liu@oracle.com>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>
> V2:
> - make sure that sequential mapping can be done
>
> block/blk-mq-cpumap.c | 29 ++++++++++++++++++++++-------
> 1 file changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
> index f945621a0e8f..0157f2b3485a 100644
> --- a/block/blk-mq-cpumap.c
> +++ b/block/blk-mq-cpumap.c
> @@ -15,10 +15,10 @@
> #include "blk.h"
> #include "blk-mq.h"
>
> -static int cpu_to_queue_index(struct blk_mq_queue_map *qmap,
> - unsigned int nr_queues, const int cpu)
> +static int queue_index(struct blk_mq_queue_map *qmap,
> + unsigned int nr_queues, const int q)
> {
> - return qmap->queue_offset + (cpu % nr_queues);
> + return qmap->queue_offset + (q % nr_queues);
> }
>
> static int get_first_sibling(unsigned int cpu)
> @@ -36,21 +36,36 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
> {
> unsigned int *map = qmap->mq_map;
> unsigned int nr_queues = qmap->nr_queues;
> - unsigned int cpu, first_sibling;
> + unsigned int cpu, first_sibling, q = 0;
> +
> + for_each_possible_cpu(cpu)
> + map[cpu] = -1;
> +
> + /*
> + * Spread queues among present CPUs first for minimizing
> + * count of dead queues which are mapped by all un-present CPUs
> + */
> + for_each_present_cpu(cpu) {
> + if (q >= nr_queues)
> + break;
> + map[cpu] = queue_index(qmap, nr_queues, q++);
> + }
>
> for_each_possible_cpu(cpu) {
> + if (map[cpu] != -1)
> + continue;
> /*
> * First do sequential mapping between CPUs and queues.
> * In case we still have CPUs to map, and we have some number of
> * threads per cores then map sibling threads to the same queue
> * for performance optimizations.
> */
> - if (cpu < nr_queues) {
> - map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
> + if (q < nr_queues) {
> + map[cpu] = queue_index(qmap, nr_queues, q++);
Yeah, that's what I was trying to say.
> } else {
> first_sibling = get_first_sibling(cpu);
> if (first_sibling == cpu)
> - map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
> + map[cpu] = queue_index(qmap, nr_queues, q++);
> else
> map[cpu] = map[first_sibling];
> }
>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH V2] blk-mq: balance mapping between present CPUs and queues
2019-07-25 9:41 [PATCH V2] blk-mq: balance mapping between present CPUs and queues Ming Lei
2019-07-25 9:50 ` Bob Liu
@ 2019-08-05 0:57 ` Ming Lei
2019-08-05 3:43 ` Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Ming Lei @ 2019-08-05 0:57 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block, Yi Zhang, Bob Liu
On Thu, Jul 25, 2019 at 05:41:46PM +0800, Ming Lei wrote:
> Spread queues among present CPUs first, then building mapping on other
> non-present CPUs.
>
> So we can minimize count of dead queues which are mapped by un-present
> CPUs only. Then bad IO performance can be avoided by unbalanced mapping
> between present CPUs and queues.
>
> The similar policy has been applied on Managed IRQ affinity.
>
> Reported-by: Yi Zhang <yi.zhang@redhat.com>
> Cc: Yi Zhang <yi.zhang@redhat.com>
> Cc: Bob Liu <bob.liu@oracle.com>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>
> V2:
> - make sure that sequential mapping can be done
>
> block/blk-mq-cpumap.c | 29 ++++++++++++++++++++++-------
> 1 file changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
> index f945621a0e8f..0157f2b3485a 100644
> --- a/block/blk-mq-cpumap.c
> +++ b/block/blk-mq-cpumap.c
> @@ -15,10 +15,10 @@
> #include "blk.h"
> #include "blk-mq.h"
>
> -static int cpu_to_queue_index(struct blk_mq_queue_map *qmap,
> - unsigned int nr_queues, const int cpu)
> +static int queue_index(struct blk_mq_queue_map *qmap,
> + unsigned int nr_queues, const int q)
> {
> - return qmap->queue_offset + (cpu % nr_queues);
> + return qmap->queue_offset + (q % nr_queues);
> }
>
> static int get_first_sibling(unsigned int cpu)
> @@ -36,21 +36,36 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
> {
> unsigned int *map = qmap->mq_map;
> unsigned int nr_queues = qmap->nr_queues;
> - unsigned int cpu, first_sibling;
> + unsigned int cpu, first_sibling, q = 0;
> +
> + for_each_possible_cpu(cpu)
> + map[cpu] = -1;
> +
> + /*
> + * Spread queues among present CPUs first for minimizing
> + * count of dead queues which are mapped by all un-present CPUs
> + */
> + for_each_present_cpu(cpu) {
> + if (q >= nr_queues)
> + break;
> + map[cpu] = queue_index(qmap, nr_queues, q++);
> + }
>
> for_each_possible_cpu(cpu) {
> + if (map[cpu] != -1)
> + continue;
> /*
> * First do sequential mapping between CPUs and queues.
> * In case we still have CPUs to map, and we have some number of
> * threads per cores then map sibling threads to the same queue
> * for performance optimizations.
> */
> - if (cpu < nr_queues) {
> - map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
> + if (q < nr_queues) {
> + map[cpu] = queue_index(qmap, nr_queues, q++);
> } else {
> first_sibling = get_first_sibling(cpu);
> if (first_sibling == cpu)
> - map[cpu] = cpu_to_queue_index(qmap, nr_queues, cpu);
> + map[cpu] = queue_index(qmap, nr_queues, q++);
> else
> map[cpu] = map[first_sibling];
> }
Hi Jens,
Could you consider to merge this patch to 5.4?
Thanks,
Ming
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH V2] blk-mq: balance mapping between present CPUs and queues
2019-07-25 9:41 [PATCH V2] blk-mq: balance mapping between present CPUs and queues Ming Lei
2019-07-25 9:50 ` Bob Liu
2019-08-05 0:57 ` Ming Lei
@ 2019-08-05 3:43 ` Jens Axboe
2 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2019-08-05 3:43 UTC (permalink / raw)
To: Ming Lei; +Cc: linux-block, Yi Zhang, Bob Liu
On 7/25/19 2:41 AM, Ming Lei wrote:
> Spread queues among present CPUs first, then building mapping on other
> non-present CPUs.
>
> So we can minimize count of dead queues which are mapped by un-present
> CPUs only. Then bad IO performance can be avoided by unbalanced mapping
> between present CPUs and queues.
>
> The similar policy has been applied on Managed IRQ affinity.
LGTM, queued up for some testing.
--
Jens Axboe
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-07-25 9:41 [PATCH V2] blk-mq: balance mapping between present CPUs and queues Ming Lei
2019-07-25 9:50 ` Bob Liu
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2019-08-05 3:43 ` Jens Axboe
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