From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Bob Liu <bob.liu@oracle.com>
Cc: xen-devel@lists.xen.org, linux-kernel@vger.kernel.org,
roger.pau@citrix.com, felipe.franciosi@citrix.com, axboe@fb.com,
avanzini.arianna@gmail.com, rafal.mielniczuk@citrix.com,
jonathan.davies@citrix.com, david.vrabel@citrix.com
Subject: Re: [PATCH v4 10/10] xen/blkback: make pool of persistent grants and free pages per-queue
Date: Wed, 4 Nov 2015 21:43:15 -0500 [thread overview]
Message-ID: <20151105024314.GD3949@x230.dumpdata.com> (raw)
In-Reply-To: <1446438106-20171-11-git-send-email-bob.liu@oracle.com>
On Mon, Nov 02, 2015 at 12:21:46PM +0800, Bob Liu wrote:
> Make pool of persistent grants and free pages per-queue/ring instead of
> per-device to get better scalability.
How much better scalability do we get?
.. snip ..
>
>
> /*
> - * pers_gnts_lock must be used around all the persistent grant helpers
> - * because blkback may use multi-thread/queue for each backend.
> + * We don't need locking around the persistent grant helpers
> + * because blkback uses a single-thread for each backed, so we
s/backed/backend/
> + * can be sure that this functions will never be called recursively.
> + *
> + * The only exception to that is put_persistent_grant, that can be called
> + * from interrupt context (by xen_blkbk_unmap), so we have to use atomic
> + * bit operations to modify the flags of a persistent grant and to count
> + * the number of used grants.
> */
..snip..
> --- a/drivers/block/xen-blkback/common.h
> +++ b/drivers/block/xen-blkback/common.h
> @@ -282,6 +282,22 @@ struct xen_blkif_ring {
> spinlock_t pending_free_lock;
> wait_queue_head_t pending_free_wq;
>
> + /* buffer of free pages to map grant refs */
Full stop.
> + spinlock_t free_pages_lock;
> + int free_pages_num;
> + struct list_head free_pages;
> +
> + /* tree to store persistent grants */
Full stop.
> + spinlock_t pers_gnts_lock;
> + struct rb_root persistent_gnts;
> + unsigned int persistent_gnt_c;
> + atomic_t persistent_gnt_in_use;
> + unsigned long next_lru;
> +
> + /* used by the kworker that offload work from the persistent purge */
Full stop.
> + struct list_head persistent_purge_list;
> + struct work_struct persistent_purge_work;
> +
> /* statistics */
> unsigned long st_print;
> unsigned long long st_rd_req;
next prev parent reply other threads:[~2015-11-05 2:43 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-02 4:21 [PATCH v4 00/10] xen-block: multi hardware-queues/rings support Bob Liu
2015-11-02 4:21 ` [PATCH v4 01/10] xen/blkif: document blkif multi-queue/ring extension Bob Liu
2015-11-02 4:21 ` [PATCH v4 02/10] xen/blkfront: separate per ring information out of device info Bob Liu
2015-11-02 4:49 ` kbuild test robot
2015-11-02 5:33 ` Bob Liu
2015-11-02 4:21 ` [PATCH v4 03/10] xen/blkfront: pseudo support for multi hardware queues/rings Bob Liu
[not found] ` <20151103194436.GE28527@char.us.oracle.com>
2015-11-04 1:01 ` Bob Liu
2015-11-02 4:21 ` [PATCH v4 04/10] xen/blkfront: split per device io_lock Bob Liu
[not found] ` <20151103200902.GF28527@char.us.oracle.com>
2015-11-04 1:07 ` Bob Liu
2015-11-04 1:51 ` Konrad Rzeszutek Wilk
2015-11-02 4:21 ` [PATCH v4 05/10] xen/blkfront: negotiate number of queues/rings to be used with backend Bob Liu
[not found] ` <20151103204029.GH28527@char.us.oracle.com>
2015-11-04 1:11 ` Bob Liu
2015-11-04 1:53 ` Konrad Rzeszutek Wilk
2015-11-02 4:21 ` [PATCH v4 06/10] xen/blkback: separate ring information out of struct xen_blkif Bob Liu
2015-11-02 4:21 ` [PATCH v4 07/10] xen/blkback: pseudo support for multi hardware queues/rings Bob Liu
2015-11-05 2:30 ` Konrad Rzeszutek Wilk
2015-11-05 3:02 ` Bob Liu
2015-11-05 3:24 ` Konrad Rzeszutek Wilk
2015-11-02 4:21 ` [PATCH v4 08/10] xen/blkback: get the number of hardware queues/rings from blkfront Bob Liu
2015-11-05 2:37 ` Konrad Rzeszutek Wilk
2015-11-02 4:21 ` [PATCH v4 09/10] xen/blkfront: make persistent grants per-queue Bob Liu
2015-11-05 2:39 ` Konrad Rzeszutek Wilk
2015-11-02 4:21 ` [PATCH v4 10/10] xen/blkback: make pool of persistent grants and free pages per-queue Bob Liu
2015-11-05 2:43 ` Konrad Rzeszutek Wilk [this message]
2015-11-05 2:46 ` Bob Liu
2015-11-05 19:50 ` Konrad Rzeszutek Wilk
2015-11-02 11:19 ` [Xen-devel] [PATCH v4 00/10] xen-block: multi hardware-queues/rings support Julien Grall
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