[PATCH v2] xen-blkback: allocate list of pending reqs in small chunks
From: Roger Pau Monne
Date: Fri Apr 26 2013 - 13:52:50 EST
Allocate pending requests in smaller chunks instead of allocating them
all at the same time.
This change also removes the global array of pending_reqs, it is no
longer necessay.
Variables related to the grant mapping have been grouped into a struct
called "grant_page", this allows to allocate them in smaller chunks,
and also improves memory locality.
Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
Changes since v1:
* Remove stray pr_alert.
---
drivers/block/xen-blkback/blkback.c | 92 +++++++++++++++--------------------
drivers/block/xen-blkback/common.h | 18 +++---
drivers/block/xen-blkback/xenbus.c | 74 +++++++++++++++++++++------
3 files changed, 106 insertions(+), 78 deletions(-)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 1ebc0aa..e79ab45 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -641,9 +641,7 @@ purge_gnt_list:
* used in the 'pending_req'.
*/
static void xen_blkbk_unmap(struct xen_blkif *blkif,
- grant_handle_t handles[],
- struct page *pages[],
- struct persistent_gnt *persistent_gnts[],
+ struct grant_page *pages[],
int num)
{
struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
@@ -652,16 +650,16 @@ static void xen_blkbk_unmap(struct xen_blkif *blkif,
int ret;
for (i = 0; i < num; i++) {
- if (persistent_gnts[i] != NULL) {
- put_persistent_gnt(blkif, persistent_gnts[i]);
+ if (pages[i]->persistent_gnt != NULL) {
+ put_persistent_gnt(blkif, pages[i]->persistent_gnt);
continue;
}
- if (handles[i] == BLKBACK_INVALID_HANDLE)
+ if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
continue;
- unmap_pages[invcount] = pages[i];
- gnttab_set_unmap_op(&unmap[invcount], vaddr(pages[i]),
- GNTMAP_host_map, handles[i]);
- handles[i] = BLKBACK_INVALID_HANDLE;
+ unmap_pages[invcount] = pages[i]->page;
+ gnttab_set_unmap_op(&unmap[invcount], vaddr(pages[i]->page),
+ GNTMAP_host_map, pages[i]->handle);
+ pages[i]->handle = BLKBACK_INVALID_HANDLE;
if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
ret = gnttab_unmap_refs(unmap, NULL, unmap_pages,
invcount);
@@ -677,10 +675,8 @@ static void xen_blkbk_unmap(struct xen_blkif *blkif,
}
}
-static int xen_blkbk_map(struct xen_blkif *blkif, grant_ref_t grefs[],
- struct persistent_gnt *persistent_gnts[],
- grant_handle_t handles[],
- struct page *pages[],
+static int xen_blkbk_map(struct xen_blkif *blkif,
+ struct grant_page *pages[],
int num, bool ro)
{
struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
@@ -707,26 +703,26 @@ again:
if (use_persistent_gnts)
persistent_gnt = get_persistent_gnt(
blkif,
- grefs[i]);
+ pages[i]->gref);
if (persistent_gnt) {
/*
* We are using persistent grants and
* the grant is already mapped
*/
- pages[i] = persistent_gnt->page;
- persistent_gnts[i] = persistent_gnt;
+ pages[i]->page = persistent_gnt->page;
+ pages[i]->persistent_gnt = persistent_gnt;
} else {
- if (get_free_page(blkif, &pages[i]))
+ if (get_free_page(blkif, &pages[i]->page))
goto out_of_memory;
- addr = vaddr(pages[i]);
- pages_to_gnt[segs_to_map] = pages[i];
- persistent_gnts[i] = NULL;
+ addr = vaddr(pages[i]->page);
+ pages_to_gnt[segs_to_map] = pages[i]->page;
+ pages[i]->persistent_gnt = NULL;
flags = GNTMAP_host_map;
if (!use_persistent_gnts && ro)
flags |= GNTMAP_readonly;
gnttab_set_map_op(&map[segs_to_map++], addr,
- flags, grefs[i],
+ flags, pages[i]->gref,
blkif->domid);
}
map_until = i + 1;
@@ -745,16 +741,16 @@ again:
* the page from the other domain.
*/
for (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) {
- if (!persistent_gnts[seg_idx]) {
+ if (!pages[seg_idx]->persistent_gnt) {
/* This is a newly mapped grant */
BUG_ON(new_map_idx >= segs_to_map);
if (unlikely(map[new_map_idx].status != 0)) {
pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
- handles[seg_idx] = BLKBACK_INVALID_HANDLE;
+ pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
ret |= 1;
goto next;
}
- handles[seg_idx] = map[new_map_idx].handle;
+ pages[seg_idx]->handle = map[new_map_idx].handle;
} else {
continue;
}
@@ -776,14 +772,14 @@ again:
}
persistent_gnt->gnt = map[new_map_idx].ref;
persistent_gnt->handle = map[new_map_idx].handle;
- persistent_gnt->page = pages[seg_idx];
+ persistent_gnt->page = pages[seg_idx]->page;
if (add_persistent_gnt(blkif,
persistent_gnt)) {
kfree(persistent_gnt);
persistent_gnt = NULL;
goto next;
}
- persistent_gnts[seg_idx] = persistent_gnt;
+ pages[seg_idx]->persistent_gnt = persistent_gnt;
pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
persistent_gnt->gnt, blkif->persistent_gnt_c,
xen_blkif_max_pgrants);
@@ -814,15 +810,11 @@ out_of_memory:
return -ENOMEM;
}
-static int xen_blkbk_map_seg(struct pending_req *pending_req,
- struct seg_buf seg[],
- struct page *pages[])
+static int xen_blkbk_map_seg(struct pending_req *pending_req)
{
int rc;
- rc = xen_blkbk_map(pending_req->blkif, pending_req->grefs,
- pending_req->persistent_gnts,
- pending_req->grant_handles, pending_req->pages,
+ rc = xen_blkbk_map(pending_req->blkif, pending_req->segments,
pending_req->nr_pages,
(pending_req->operation != BLKIF_OP_READ));
@@ -834,9 +826,7 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
struct seg_buf seg[],
struct phys_req *preq)
{
- struct persistent_gnt **persistent =
- pending_req->indirect_persistent_gnts;
- struct page **pages = pending_req->indirect_pages;
+ struct grant_page **pages = pending_req->indirect_pages;
struct xen_blkif *blkif = pending_req->blkif;
int indirect_grefs, rc, n, nseg, i;
struct blkif_request_segment_aligned *segments = NULL;
@@ -845,9 +835,10 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
indirect_grefs = INDIRECT_PAGES(nseg);
BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
- rc = xen_blkbk_map(blkif, req->u.indirect.indirect_grefs,
- persistent, pending_req->indirect_handles,
- pages, indirect_grefs, true);
+ for (i = 0; i < indirect_grefs; i++)
+ pages[i]->gref = req->u.indirect.indirect_grefs[i];
+
+ rc = xen_blkbk_map(blkif, pages, indirect_grefs, true);
if (rc)
goto unmap;
@@ -856,10 +847,10 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
/* Map indirect segments */
if (segments)
kunmap_atomic(segments);
- segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]);
+ segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page);
}
i = n % SEGS_PER_INDIRECT_FRAME;
- pending_req->grefs[n] = segments[i].gref;
+ pending_req->segments[n]->gref = segments[i].gref;
seg[n].nsec = segments[i].last_sect -
segments[i].first_sect + 1;
seg[n].offset = (segments[i].first_sect << 9);
@@ -874,8 +865,7 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
unmap:
if (segments)
kunmap_atomic(segments);
- xen_blkbk_unmap(blkif, pending_req->indirect_handles,
- pages, persistent, indirect_grefs);
+ xen_blkbk_unmap(blkif, pages, indirect_grefs);
return rc;
}
@@ -965,9 +955,8 @@ static void __end_block_io_op(struct pending_req *pending_req, int error)
* the proper response on the ring.
*/
if (atomic_dec_and_test(&pending_req->pendcnt)) {
- xen_blkbk_unmap(pending_req->blkif, pending_req->grant_handles,
- pending_req->pages,
- pending_req->persistent_gnts,
+ xen_blkbk_unmap(pending_req->blkif,
+ pending_req->segments,
pending_req->nr_pages);
make_response(pending_req->blkif, pending_req->id,
pending_req->operation, pending_req->status);
@@ -1104,7 +1093,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
int operation;
struct blk_plug plug;
bool drain = false;
- struct page **pages = pending_req->pages;
+ struct grant_page **pages = pending_req->segments;
unsigned short req_operation;
req_operation = req->operation == BLKIF_OP_INDIRECT ?
@@ -1165,7 +1154,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
preq.dev = req->u.rw.handle;
preq.sector_number = req->u.rw.sector_number;
for (i = 0; i < nseg; i++) {
- pending_req->grefs[i] = req->u.rw.seg[i].gref;
+ pages[i]->gref = req->u.rw.seg[i].gref;
seg[i].nsec = req->u.rw.seg[i].last_sect -
req->u.rw.seg[i].first_sect + 1;
seg[i].offset = (req->u.rw.seg[i].first_sect << 9);
@@ -1216,7 +1205,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
* the hypercall to unmap the grants - that is all done in
* xen_blkbk_unmap.
*/
- if (xen_blkbk_map_seg(pending_req, seg, pages))
+ if (xen_blkbk_map_seg(pending_req))
goto fail_flush;
/*
@@ -1228,7 +1217,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
for (i = 0; i < nseg; i++) {
while ((bio == NULL) ||
(bio_add_page(bio,
- pages[i],
+ pages[i]->page,
seg[i].nsec << 9,
seg[i].offset) == 0)) {
@@ -1277,8 +1266,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
return 0;
fail_flush:
- xen_blkbk_unmap(blkif, pending_req->grant_handles,
- pending_req->pages, pending_req->persistent_gnts,
+ xen_blkbk_unmap(blkif, pending_req->segments,
pending_req->nr_pages);
fail_response:
/* Haven't submitted any bio's yet. */
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 1ac53da..c6b4cb9 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -297,8 +297,6 @@ 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. */
@@ -323,6 +321,13 @@ struct seg_buf {
unsigned int nsec;
};
+struct grant_page {
+ struct page *page;
+ struct persistent_gnt *persistent_gnt;
+ grant_handle_t handle;
+ grant_ref_t gref;
+};
+
/*
* 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
@@ -337,14 +342,9 @@ struct pending_req {
unsigned short operation;
int status;
struct list_head free_list;
- struct page *pages[MAX_INDIRECT_SEGMENTS];
- struct persistent_gnt *persistent_gnts[MAX_INDIRECT_SEGMENTS];
- grant_handle_t grant_handles[MAX_INDIRECT_SEGMENTS];
- grant_ref_t grefs[MAX_INDIRECT_SEGMENTS];
+ struct grant_page *segments[MAX_INDIRECT_SEGMENTS];
/* Indirect descriptors */
- struct persistent_gnt *indirect_persistent_gnts[MAX_INDIRECT_PAGES];
- struct page *indirect_pages[MAX_INDIRECT_PAGES];
- grant_handle_t indirect_handles[MAX_INDIRECT_PAGES];
+ struct grant_page *indirect_pages[MAX_INDIRECT_PAGES];
struct seg_buf seg[MAX_INDIRECT_SEGMENTS];
struct bio *biolist[MAX_INDIRECT_SEGMENTS];
};
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index afab208..4a4749c 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -105,7 +105,8 @@ static void xen_update_blkif_status(struct xen_blkif *blkif)
static struct xen_blkif *xen_blkif_alloc(domid_t domid)
{
struct xen_blkif *blkif;
- int i;
+ struct pending_req *req, *n;
+ int i, j;
BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
@@ -127,22 +128,51 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
blkif->free_pages_num = 0;
atomic_set(&blkif->persistent_gnt_in_use, 0);
- blkif->pending_reqs = kcalloc(XEN_BLKIF_REQS,
- sizeof(blkif->pending_reqs[0]),
- GFP_KERNEL);
- if (!blkif->pending_reqs) {
- kmem_cache_free(xen_blkif_cachep, blkif);
- return ERR_PTR(-ENOMEM);
- }
INIT_LIST_HEAD(&blkif->pending_free);
+
+ for (i = 0; i < XEN_BLKIF_REQS; i++) {
+ req = kzalloc(sizeof(*req), GFP_KERNEL);
+ if (!req)
+ goto fail;
+ list_add_tail(&req->free_list,
+ &blkif->pending_free);
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
+ req->segments[j] = kzalloc(sizeof(*req->segments[0]),
+ GFP_KERNEL);
+ if (!req->segments[j])
+ goto fail;
+ }
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
+ req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
+ GFP_KERNEL);
+ if (!req->indirect_pages[j])
+ goto fail;
+ }
+ }
spin_lock_init(&blkif->pending_free_lock);
init_waitqueue_head(&blkif->pending_free_wq);
- for (i = 0; i < XEN_BLKIF_REQS; i++)
- list_add_tail(&blkif->pending_reqs[i].free_list,
- &blkif->pending_free);
-
return blkif;
+
+fail:
+ list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
+ list_del(&req->free_list);
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
+ if (!req->segments[j])
+ break;
+ kfree(req->segments[j]);
+ }
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
+ if (!req->indirect_pages[j])
+ break;
+ kfree(req->indirect_pages[j]);
+ }
+ kfree(req);
+ }
+
+ kmem_cache_free(xen_blkif_cachep, blkif);
+
+ return ERR_PTR(-ENOMEM);
}
static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
@@ -221,18 +251,28 @@ static void xen_blkif_disconnect(struct xen_blkif *blkif)
static void xen_blkif_free(struct xen_blkif *blkif)
{
- struct pending_req *req;
- int i = 0;
+ struct pending_req *req, *n;
+ int i = 0, j;
if (!atomic_dec_and_test(&blkif->refcnt))
BUG();
/* Check that there is no request in use */
- list_for_each_entry(req, &blkif->pending_free, free_list)
+ list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
+ list_del(&req->free_list);
+
+ for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
+ kfree(req->segments[j]);
+
+ for (j = 0; j < MAX_INDIRECT_PAGES; j++)
+ kfree(req->indirect_pages[j]);
+
+ kfree(req);
i++;
- BUG_ON(i != XEN_BLKIF_REQS);
+ }
+
+ WARN_ON(i != XEN_BLKIF_REQS);
- kfree(blkif->pending_reqs);
kmem_cache_free(xen_blkif_cachep, blkif);
}
--
1.7.7.5 (Apple Git-26)
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