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| author | Roger Pau Monne <roger.pau@citrix.com> | 2013-04-17 20:18:59 +0200 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-04-18 15:29:25 +0200 |
| commit | bf0720c48c7cefd127ed2329e6d0e40b39fa4d0e (patch) | |
| tree | faece56f2dd1be19c6ae40676210004a599ed792 /drivers/block/xen-blkback/common.h | |
| parent | xen-blkback: move pending handles list from blkbk to pending_req (diff) | |
| download | linux-bf0720c48c7cefd127ed2329e6d0e40b39fa4d0e.tar.xz linux-bf0720c48c7cefd127ed2329e6d0e40b39fa4d0e.zip | |
xen-blkback: make the queue of free requests per backend
Remove the last dependency from blkbk by moving the list of free
requests to blkif. This change reduces the contention on the list of
available requests.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xen.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/block/xen-blkback/common.h')
| -rw-r--r-- | drivers/block/xen-blkback/common.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index af9bed48f773..e33fafa0facd 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -192,6 +192,9 @@ struct backend_info; */ #define PERSISTENT_GNT_WAS_ACTIVE 1 +/* Number of requests that we can fit in a ring */ +#define XEN_BLKIF_REQS 32 + struct persistent_gnt { struct page *page; grant_ref_t gnt; @@ -242,6 +245,14 @@ struct xen_blkif { int free_pages_num; struct list_head free_pages; + /* Allocation of pending_reqs */ + struct pending_req *pending_reqs; + /* List of all 'pending_req' available */ + struct list_head pending_free; + /* And its spinlock. */ + spinlock_t pending_free_lock; + wait_queue_head_t pending_free_wq; + /* statistics */ unsigned long st_print; unsigned long long st_rd_req; @@ -255,6 +266,25 @@ struct xen_blkif { wait_queue_head_t waiting_to_free; }; +/* + * Each outstanding request that we've passed to the lower device layers has a + * 'pending_req' allocated to it. Each buffer_head that completes decrements + * the pendcnt towards zero. When it hits zero, the specified domain has a + * response queued for it, with the saved 'id' passed back. + */ +struct pending_req { + struct xen_blkif *blkif; + u64 id; + int nr_pages; + atomic_t pendcnt; + unsigned short operation; + int status; + struct list_head free_list; + struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + struct persistent_gnt *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + grant_handle_t grant_handles[BLKIF_MAX_SEGMENTS_PER_REQUEST]; +}; + #define vbd_sz(_v) ((_v)->bdev->bd_part ? \ (_v)->bdev->bd_part->nr_sects : \ |