ACK: [PATCH 2/2] Revert "UBUNTU: SAUCE: Improve Amazon EBS performance for EC2"

Colin Ian King colin.king at canonical.com
Mon Sep 17 15:29:16 UTC 2012


On 17/09/12 16:26, Stefan Bader wrote:
> This reverts commit d514f9334bc4f1097abfe5ecaf9ab091b8d0a18b as it
> is not needed/used.
>
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>   drivers/block/xen-blkfront.c     |  120 ++++++++++----------------------------
>   include/xen/interface/io/blkif.h |   12 ----
>   2 files changed, 32 insertions(+), 100 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index 43860d3..e4fb337 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -73,8 +73,7 @@ struct blk_shadow {
>   static DEFINE_MUTEX(blkfront_mutex);
>   static const struct block_device_operations xlvbd_block_fops;
>
> -#define BLK_MAX_RING_AREA_SIZE (BLKIF_MAX_NUM_RING_PAGES * PAGE_SIZE)
> -#define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, BLK_MAX_RING_AREA_SIZE)
> +#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
>
>   /*
>    * We have one of these per vbd, whether ide, scsi or 'other'.  They
> @@ -90,15 +89,14 @@ struct blkfront_info
>   	int vdevice;
>   	blkif_vdev_t handle;
>   	enum blkif_state connected;
> -	int num_ring_pages;
> -	int ring_ref[BLKIF_MAX_NUM_RING_PAGES];
> +	int ring_ref;
>   	struct blkif_front_ring ring;
>   	struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
>   	unsigned int evtchn, irq;
>   	struct request_queue *rq;
>   	struct work_struct work;
>   	struct gnttab_free_callback callback;
> -	struct blk_shadow shadow[BLK_MAX_RING_SIZE];
> +	struct blk_shadow shadow[BLK_RING_SIZE];
>   	unsigned long shadow_free;
>   	unsigned int feature_flush;
>   	unsigned int flush_op;
> @@ -137,8 +135,7 @@ static DEFINE_SPINLOCK(minor_lock);
>   static int get_id_from_freelist(struct blkfront_info *info)
>   {
>   	unsigned long free = info->shadow_free;
> -	int ring_size = __RING_SIZE((struct blkif_sring *)0, info->num_ring_pages * PAGE_SIZE);
> -	BUG_ON(free >= ring_size);
> +	BUG_ON(free >= BLK_RING_SIZE);
>   	info->shadow_free = info->shadow[free].req.u.rw.id;
>   	info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
>   	return free;
> @@ -710,8 +707,6 @@ static void blkif_restart_queue(struct work_struct *work)
>
>   static void blkif_free(struct blkfront_info *info, int suspend)
>   {
> -	int i;
> -
>   	/* Prevent new requests being issued until we fix things up. */
>   	spin_lock_irq(&info->io_lock);
>   	info->connected = suspend ?
> @@ -727,17 +722,10 @@ static void blkif_free(struct blkfront_info *info, int suspend)
>   	flush_work_sync(&info->work);
>
>   	/* Free resources associated with old device channel. */
> -	for (i = 0; i < info->num_ring_pages; i++) {
> -		/* Free resources associated with old device channel. */
> -		if (info->ring_ref[i] != GRANT_INVALID_REF) {
> -			gnttab_end_foreign_access(info->ring_ref[i], 0, 0L);
> -			info->ring_ref[i] = GRANT_INVALID_REF;
> -		}
> -	}
> -	if (info->ring.sring) {
> -		int ring_area_size = info->num_ring_pages * PAGE_SIZE;
> -		free_pages((unsigned long)info->ring.sring,
> -			   get_order(ring_area_size));
> +	if (info->ring_ref != GRANT_INVALID_REF) {
> +		gnttab_end_foreign_access(info->ring_ref, 0,
> +					  (unsigned long)info->ring.sring);
> +		info->ring_ref = GRANT_INVALID_REF;
>   		info->ring.sring = NULL;
>   	}
>   	if (info->irq)
> @@ -874,32 +862,27 @@ static int setup_blkring(struct xenbus_device *dev,
>   			 struct blkfront_info *info)
>   {
>   	struct blkif_sring *sring;
> -	int i, order, err;
> -	int ring_area_size = info->num_ring_pages * PAGE_SIZE;
> +	int err;
>
> -	for (i = 0; i < info->num_ring_pages; i++) {
> -		info->ring_ref[i] = GRANT_INVALID_REF;
> -	}
> +	info->ring_ref = GRANT_INVALID_REF;
>
> -	order = get_order(ring_area_size);
> -	sring = (struct blkif_sring *)__get_free_pages(GFP_KERNEL, order);
> +	sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
>   	if (!sring) {
>   		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
>   		return -ENOMEM;
>   	}
>   	SHARED_RING_INIT(sring);
> -	FRONT_RING_INIT(&info->ring, sring, ring_area_size);
> -
> -	for (i = 0; i < info->num_ring_pages; i++) {
> -		unsigned long addr = (unsigned long)info->ring.sring + i * PAGE_SIZE;
> -		err = xenbus_grant_ring(dev, virt_to_mfn(addr));
> -		if (err < 0) {
> -			free_pages((unsigned long)sring, order);
> -			info->ring.sring = NULL;
> -			goto fail;
> -		}
> -		info->ring_ref[i] = err;
> +	FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
> +
> +	sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
> +
> +	err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
> +	if (err < 0) {
> +		free_page((unsigned long)sring);
> +		info->ring.sring = NULL;
> +		goto fail;
>   	}
> +	info->ring_ref = err;
>
>   	err = xenbus_alloc_evtchn(dev, &info->evtchn);
>   	if (err)
> @@ -928,13 +911,7 @@ static int talk_to_blkback(struct xenbus_device *dev,
>   {
>   	const char *message = NULL;
>   	struct xenbus_transaction xbt;
> -	int err, i;
> -
> -	BUILD_BUG_ON(BLKIF_MAX_NUM_RING_PAGES != 1 &&
> -	       BLKIF_MAX_NUM_RING_PAGES != 2 &&
> -	       BLKIF_MAX_NUM_RING_PAGES != 4 &&
> -	       BLKIF_MAX_NUM_RING_PAGES != 8 &&
> -	       BLKIF_MAX_NUM_RING_PAGES != 16);
> +	int err;
>
>   	/* Create shared ring, alloc event channel. */
>   	err = setup_blkring(dev, info);
> @@ -948,30 +925,11 @@ again:
>   		goto destroy_blkring;
>   	}
>
> -	if (info->num_ring_pages == 1) {
> -		err = xenbus_printf(xbt, dev->nodename,
> -				"ring-ref", "%u", info->ring_ref[0]);
> -		if (err) {
> -			message = "writing ring-ref";
> -			goto abort_transaction;
> -		}
> -	} else {
> -		err = xenbus_printf(xbt, dev->nodename, "num-ring-pages", "%u",
> -				info->num_ring_pages);
> -		if (err) {
> -			message = "writing num-ring-pages";
> -			goto abort_transaction;
> -		}
> -		for (i = 0; i < info->num_ring_pages; i++) {
> -			char buf[16];
> -			snprintf(buf, sizeof(buf), "ring-ref%d", i);
> -			err = xenbus_printf(xbt, dev->nodename, buf, "%u",
> -					info->ring_ref[i]);
> -			if (err) {
> -				message = "writing ring-refs";
> -				goto abort_transaction;
> -			}
> -		}
> +	err = xenbus_printf(xbt, dev->nodename,
> +			    "ring-ref", "%u", info->ring_ref);
> +	if (err) {
> +		message = "writing ring-ref";
> +		goto abort_transaction;
>   	}
>   	err = xenbus_printf(xbt, dev->nodename,
>   			    "event-channel", "%u", info->evtchn);
> @@ -1019,7 +977,6 @@ static int blkfront_probe(struct xenbus_device *dev,
>   {
>   	int err, vdevice, i;
>   	struct blkfront_info *info;
> -	int ring_size, max_ring_pages;
>
>   	/* FIXME: Use dynamic device id if this is not set. */
>   	err = xenbus_scanf(XBT_NIL, dev->nodename,
> @@ -1033,10 +990,6 @@ static int blkfront_probe(struct xenbus_device *dev,
>   			return err;
>   		}
>   	}
> -	err = xenbus_scanf(XBT_NIL, dev->otherend,
> -			   "max-ring-pages", "%u", &max_ring_pages);
> -	if (err != 1)
> -		max_ring_pages = 1;
>
>   	if (xen_hvm_domain()) {
>   		char *type;
> @@ -1080,13 +1033,9 @@ static int blkfront_probe(struct xenbus_device *dev,
>   	info->connected = BLKIF_STATE_DISCONNECTED;
>   	INIT_WORK(&info->work, blkif_restart_queue);
>
> -	info->num_ring_pages = min(max_ring_pages, BLKIF_MAX_NUM_RING_PAGES);
> -
> -	ring_size = __RING_SIZE((struct blkif_sring *)0,
> -				info->num_ring_pages * PAGE_SIZE);
> -	for (i = 0; i < ring_size; i++)
> +	for (i = 0; i < BLK_RING_SIZE; i++)
>   		info->shadow[i].req.u.rw.id = i+1;
> -	info->shadow[ring_size-1].req.u.rw.id = 0x0fffffff;
> +	info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
>
>   	/* Front end dir is a number, which is used as the id. */
>   	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
> @@ -1099,9 +1048,6 @@ static int blkfront_probe(struct xenbus_device *dev,
>   		return err;
>   	}
>
> -	printk(KERN_INFO "blkfront %s num-ring-pages %d nr_ents %d.\n",
> -		dev->nodename, info->num_ring_pages, ring_size);
> -
>   	return 0;
>   }
>
> @@ -1112,7 +1058,6 @@ static int blkif_recover(struct blkfront_info *info)
>   	struct blkif_request *req;
>   	struct blk_shadow *copy;
>   	int j;
> -	int ring_size = __RING_SIZE((struct blkif_sring *)0, info->num_ring_pages * PAGE_SIZE);
>
>   	/* Stage 1: Make a safe copy of the shadow state. */
>   	copy = kmalloc(sizeof(info->shadow),
> @@ -1123,13 +1068,13 @@ static int blkif_recover(struct blkfront_info *info)
>
>   	/* Stage 2: Set up free list. */
>   	memset(&info->shadow, 0, sizeof(info->shadow));
> -	for (i = 0; i < ring_size; i++)
> +	for (i = 0; i < BLK_RING_SIZE; i++)
>   		info->shadow[i].req.u.rw.id = i+1;
>   	info->shadow_free = info->ring.req_prod_pvt;
> -	info->shadow[ring_size-1].req.u.rw.id = 0x0fffffff;
> +	info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
>
>   	/* Stage 3: Find pending requests and requeue them. */
> -	for (i = 0; i < ring_size; i++) {
> +	for (i = 0; i < BLK_RING_SIZE; i++) {
>   		/* Not in use? */
>   		if (!copy[i].request)
>   			continue;
> @@ -1600,4 +1545,3 @@ MODULE_LICENSE("GPL");
>   MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
>   MODULE_ALIAS("xen:vbd");
>   MODULE_ALIAS("xenblk");
> -
> diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
> index 31063bd..ee338bf 100644
> --- a/include/xen/interface/io/blkif.h
> +++ b/include/xen/interface/io/blkif.h
> @@ -168,18 +168,6 @@ struct blkif_response {
>
>   DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
>
> -/*
> - * Maximum number of pages used for a blkif ring
> - * max-ring-pages advertised by blkback to blkfront may be lowered at blkback
> - * mod load time.   Load time param set to default.
> - */
> -#define BLKIF_MAX_NUM_RING_PAGES 16
> -#define BLKIF_MAX_NUM_RING_PAGES_DFLT 4
> -#if BLKIF_MAX_NUM_RING_PAGES < BLKIF_MAX_NUM_RING_PAGES_DFLT
> -#undef BLKIF_MAX_NUM_RING_PAGES_DFLT
> -#define BLKIF_MAX_NUM_RING_PAGES_DFLT BLKIF_MAX_NUM_RING_PAGES
> -#endif
> -
>   #define VDISK_CDROM        0x1
>   #define VDISK_REMOVABLE    0x2
>   #define VDISK_READONLY     0x4
>





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