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xen/blkfront: make persistent grants pool per-queue

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Make persistent grants per-queue/ring instead of per-device, so that we can
drop the 'dev_lock' and get better scalability.

Test was done based on null_blk driver:
dom0: v4.2-rc8 16vcpus 10GB "modprobe null_blk"
domu: v4.2-rc8 16vcpus 10GB

[test]
rw=read
direct=1
ioengine=libaio
bs=4k
time_based
runtime=30
filename=/dev/xvdb
numjobs=16
iodepth=64
iodepth_batch=64
iodepth_batch_complete=64
group_reporting

Queues:			  1 	   4 	  	  8 	 	 16
Iops orig(k):		810 	1064 		780 		700
Iops patched(k):	810     1230(~20%)	1024(~20%)	850(~20%)

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Bob Liu 2015-11-16 16:51:39 -05:00 committed by Konrad Rzeszutek Wilk
parent 75f070b396
commit 73716df7da
1 changed files with 43 additions and 67 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

110
drivers/block/xen-blkfront.c
View File

@ -142,6 +142,8 @@ struct blkfront_ring_info {
struct gnttab_free_callback callback;
struct blk_shadow shadow[BLK_MAX_RING_SIZE];
struct list_head indirect_pages;
struct list_head grants;
unsigned int persistent_gnts_c;
unsigned long shadow_free;
struct blkfront_info *dev_info;
};
@ -162,13 +164,6 @@ struct blkfront_info
/* Number of pages per ring buffer. */
unsigned int nr_ring_pages;
struct request_queue *rq;
/*
* Lock to protect info->grants list and persistent_gnts_c shared by all
* rings.
*/
spinlock_t dev_lock;
struct list_head grants;
unsigned int persistent_gnts_c;
unsigned int feature_flush;
unsigned int feature_discard:1;
unsigned int feature_secdiscard:1;
@ -272,9 +267,7 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
}
gnt_list_entry->gref = GRANT_INVALID_REF;
spin_lock_irq(&info->dev_lock);
list_add(&gnt_list_entry->node, &info->grants);
spin_unlock_irq(&info->dev_lock);
list_add(&gnt_list_entry->node, &rinfo->grants);
i++;
}
@ -282,10 +275,8 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
out_of_memory:
list_for_each_entry_safe(gnt_list_entry, n,
&info->grants, node) {
spin_lock_irq(&info->dev_lock);
&rinfo->grants, node) {
list_del(&gnt_list_entry->node);
spin_unlock_irq(&info->dev_lock);
if (info->feature_persistent)
__free_page(gnt_list_entry->page);
kfree(gnt_list_entry);
@ -295,20 +286,17 @@ out_of_memory:
return -ENOMEM;
}
static struct grant *get_free_grant(struct blkfront_info *info)
static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
{
struct grant *gnt_list_entry;
unsigned long flags;
spin_lock_irqsave(&info->dev_lock, flags);
BUG_ON(list_empty(&info->grants));
gnt_list_entry = list_first_entry(&info->grants, struct grant,
BUG_ON(list_empty(&rinfo->grants));
gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
node);
list_del(&gnt_list_entry->node);
if (gnt_list_entry->gref != GRANT_INVALID_REF)
info->persistent_gnts_c--;
spin_unlock_irqrestore(&info->dev_lock, flags);
rinfo->persistent_gnts_c--;
return gnt_list_entry;
}
@ -324,9 +312,10 @@ static inline void grant_foreign_access(const struct grant *gnt_list_entry,
static struct grant *get_grant(grant_ref_t *gref_head,
unsigned long gfn,
struct blkfront_info *info)
struct blkfront_ring_info *rinfo)
{
struct grant *gnt_list_entry = get_free_grant(info);
struct grant *gnt_list_entry = get_free_grant(rinfo);
struct blkfront_info *info = rinfo->dev_info;
if (gnt_list_entry->gref != GRANT_INVALID_REF)
return gnt_list_entry;
@ -347,9 +336,10 @@ static struct grant *get_grant(grant_ref_t *gref_head,
}
static struct grant *get_indirect_grant(grant_ref_t *gref_head,
struct blkfront_info *info)
struct blkfront_ring_info *rinfo)
{
struct grant *gnt_list_entry = get_free_grant(info);
struct grant *gnt_list_entry = get_free_grant(rinfo);
struct blkfront_info *info = rinfo->dev_info;
if (gnt_list_entry->gref != GRANT_INVALID_REF)
return gnt_list_entry;
@ -361,8 +351,8 @@ static struct grant *get_indirect_grant(grant_ref_t *gref_head,
struct page *indirect_page;
/* Fetch a pre-allocated page to use for indirect grefs */
BUG_ON(list_empty(&info->rinfo->indirect_pages));
indirect_page = list_first_entry(&info->rinfo->indirect_pages,
BUG_ON(list_empty(&rinfo->indirect_pages));
indirect_page = list_first_entry(&rinfo->indirect_pages,
struct page, lru);
list_del(&indirect_page->lru);
gnt_list_entry->page = indirect_page;
@ -543,7 +533,6 @@ static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
unsigned int grant_idx = setup->grant_idx;
struct blkif_request *ring_req = setup->ring_req;
struct blkfront_ring_info *rinfo = setup->rinfo;
struct blkfront_info *info = rinfo->dev_info;
struct blk_shadow *shadow = &rinfo->shadow[setup->id];
if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
@ -552,13 +541,13 @@ static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
kunmap_atomic(setup->segments);
n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
gnt_list_entry = get_indirect_grant(&setup->gref_head, info);
gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
shadow->indirect_grants[n] = gnt_list_entry;
setup->segments = kmap_atomic(gnt_list_entry->page);
ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
}
gnt_list_entry = get_grant(&setup->gref_head, gfn, info);
gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
ref = gnt_list_entry->gref;
shadow->grants_used[grant_idx] = gnt_list_entry;
@ -1129,7 +1118,7 @@ static void blkif_restart_queue(struct work_struct *work)
static void blkif_free_ring(struct blkfront_ring_info *rinfo)
{
struct grant *persistent_gnt;
struct grant *persistent_gnt, *n;
struct blkfront_info *info = rinfo->dev_info;
int i, j, segs;
@ -1147,6 +1136,23 @@ static void blkif_free_ring(struct blkfront_ring_info *rinfo)
}
}
/* Remove all persistent grants. */
if (!list_empty(&rinfo->grants)) {
list_for_each_entry_safe(persistent_gnt, n,
&rinfo->grants, node) {
list_del(&persistent_gnt->node);
if (persistent_gnt->gref != GRANT_INVALID_REF) {
gnttab_end_foreign_access(persistent_gnt->gref,
0, 0UL);
rinfo->persistent_gnts_c--;
}
if (info->feature_persistent)
__free_page(persistent_gnt->page);
kfree(persistent_gnt);
}
}
BUG_ON(rinfo->persistent_gnts_c != 0);
for (i = 0; i < BLK_RING_SIZE(info); i++) {
/*
* Clear persistent grants present in requests already
@ -1212,7 +1218,6 @@ free_shadow:
static void blkif_free(struct blkfront_info *info, int suspend)
{
struct grant *persistent_gnt, *n;
unsigned int i;
/* Prevent new requests being issued until we fix things up. */
@ -1222,25 +1227,6 @@ static void blkif_free(struct blkfront_info *info, int suspend)
if (info->rq)
blk_mq_stop_hw_queues(info->rq);
/* Remove all persistent grants */
spin_lock_irq(&info->dev_lock);
if (!list_empty(&info->grants)) {
list_for_each_entry_safe(persistent_gnt, n,
&info->grants, node) {
list_del(&persistent_gnt->node);
if (persistent_gnt->gref != GRANT_INVALID_REF) {
gnttab_end_foreign_access(persistent_gnt->gref,
0, 0UL);
info->persistent_gnts_c--;
}
if (info->feature_persistent)
__free_page(persistent_gnt->page);
kfree(persistent_gnt);
}
}
BUG_ON(info->persistent_gnts_c != 0);
spin_unlock_irq(&info->dev_lock);
for (i = 0; i < info->nr_rings; i++)
blkif_free_ring(&info->rinfo[i]);
@ -1281,7 +1267,6 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
int i = 0;
struct scatterlist *sg;
int num_sg, num_grant;
unsigned long flags;
struct blkfront_info *info = rinfo->dev_info;
struct copy_from_grant data = {
.s = s,
@ -1320,10 +1305,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
if (!info->feature_persistent)
pr_alert_ratelimited("backed has not unmapped grant: %u\n",
s->grants_used[i]->gref);
spin_lock_irqsave(&info->dev_lock, flags);
list_add(&s->grants_used[i]->node, &info->grants);
info->persistent_gnts_c++;
spin_unlock_irqrestore(&info->dev_lock, flags);
list_add(&s->grants_used[i]->node, &rinfo->grants);
rinfo->persistent_gnts_c++;
} else {
/*
* If the grant is not mapped by the backend we end the
@ -1333,9 +1316,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
*/
gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
s->grants_used[i]->gref = GRANT_INVALID_REF;
spin_lock_irqsave(&info->dev_lock, flags);
list_add_tail(&s->grants_used[i]->node, &info->grants);
spin_unlock_irqrestore(&info->dev_lock, flags);
list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
}
}
if (s->req.operation == BLKIF_OP_INDIRECT) {
@ -1344,10 +1325,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
if (!info->feature_persistent)
pr_alert_ratelimited("backed has not unmapped grant: %u\n",
s->indirect_grants[i]->gref);
spin_lock_irqsave(&info->dev_lock, flags);
list_add(&s->indirect_grants[i]->node, &info->grants);
info->persistent_gnts_c++;
spin_unlock_irqrestore(&info->dev_lock, flags);
list_add(&s->indirect_grants[i]->node, &rinfo->grants);
rinfo->persistent_gnts_c++;
} else {
struct page *indirect_page;
@ -1361,9 +1340,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri
list_add(&indirect_page->lru, &rinfo->indirect_pages);
}
s->indirect_grants[i]->gref = GRANT_INVALID_REF;
spin_lock_irqsave(&info->dev_lock, flags);
list_add_tail(&s->indirect_grants[i]->node, &info->grants);
spin_unlock_irqrestore(&info->dev_lock, flags);
list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
}
}
}
@ -1785,15 +1762,14 @@ static int blkfront_probe(struct xenbus_device *dev,
rinfo = &info->rinfo[r_index];
INIT_LIST_HEAD(&rinfo->indirect_pages);
INIT_LIST_HEAD(&rinfo->grants);
rinfo->dev_info = info;
INIT_WORK(&rinfo->work, blkif_restart_queue);
spin_lock_init(&rinfo->ring_lock);
}
mutex_init(&info->mutex);
spin_lock_init(&info->dev_lock);
info->vdevice = vdevice;
INIT_LIST_HEAD(&info->grants);
info->connected = BLKIF_STATE_DISCONNECTED;
/* Front end dir is a number, which is used as the id. */