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

Stefan Bader stefan.bader at canonical.com
Mon Sep 17 15:26:34 UTC 2012


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
-- 
1.7.9.5





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