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xen-blkback: allocate list of pending reqs in small chunks
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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 Monné <roger.pau@citrix.com>
Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Roger Pau Monne authored and Konrad Rzeszutek Wilk committed May 7, 2013
1 parent 402b27f commit bb642e8
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Showing 3 changed files with 106 additions and 78 deletions.
92 changes: 40 additions & 52 deletions drivers/block/xen-blkback/blkback.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -641,9 +641,7 @@ int xen_blkif_schedule(void *arg)
* 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];
Expand All @@ -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);
Expand All @@ -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];
Expand All @@ -707,26 +703,26 @@ static int xen_blkbk_map(struct xen_blkif *blkif, grant_ref_t grefs[],
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;
Expand All @@ -745,16 +741,16 @@ static int xen_blkbk_map(struct xen_blkif *blkif, grant_ref_t grefs[],
* 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;
}
Expand All @@ -776,14 +772,14 @@ static int xen_blkbk_map(struct xen_blkif *blkif, grant_ref_t grefs[],
}
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);
Expand Down Expand Up @@ -814,15 +810,11 @@ static int xen_blkbk_map(struct xen_blkif *blkif, grant_ref_t grefs[],
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));

Expand All @@ -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;
Expand All @@ -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;

Expand All @@ -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);
Expand All @@ -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;
}

Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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 ?
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;

/*
Expand All @@ -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)) {

Expand Down Expand Up @@ -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. */
Expand Down
18 changes: 9 additions & 9 deletions drivers/block/xen-blkback/common.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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. */
Expand All @@ -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
Expand All @@ -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];
};
Expand Down
74 changes: 57 additions & 17 deletions drivers/block/xen-blkback/xenbus.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand All @@ -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,
Expand Down Expand Up @@ -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);
}

Expand Down

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