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[Qemu-block] [PATCH RFC v2 18/22] block/pcache: add pcache skip large ai
From: |
Pavel Butsykin |
Subject: |
[Qemu-block] [PATCH RFC v2 18/22] block/pcache: add pcache skip large aio read |
Date: |
Mon, 29 Aug 2016 20:10:17 +0300 |
This change will allow more efficient use of cache memory and
filter the case for which the pcache isn't efficient. We miss requests
that are not required in the optimization and thereby reducing the number
of unnecessary readaheads.
Add pcache-max-aio-size open parameter.
Signed-off-by: Pavel Butsykin <address@hidden>
---
block/pcache.c | 49 ++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 40 insertions(+), 9 deletions(-)
diff --git a/block/pcache.c b/block/pcache.c
index 7a317fc..287156a 100644
--- a/block/pcache.c
+++ b/block/pcache.c
@@ -100,6 +100,7 @@ typedef struct BDRVPCacheState {
struct {
uint32_t cache_size;
uint32_t readahead_size;
+ uint32_t max_aio_size;
uint32_t lreq_pool_size;
} cfg;
@@ -144,6 +145,7 @@ static const AIOCBInfo pcache_aiocb_info = {
#define PCACHE_OPT_CACHE_SIZE "pcache-full-size"
#define PCACHE_OPT_READAHEAD_SIZE "pcache-readahead-size"
+#define PCACHE_OPT_MAX_AIO_SIZE "pcache-max-aio-size"
static QemuOptsList runtime_opts = {
.name = "pcache",
@@ -164,6 +166,11 @@ static QemuOptsList runtime_opts = {
.type = QEMU_OPT_SIZE,
.help = "Prefetch cache readahead size",
},
+ {
+ .name = PCACHE_OPT_MAX_AIO_SIZE,
+ .type = QEMU_OPT_SIZE,
+ .help = "Maximum size of aio which is handled by pcache",
+ },
{ /* end of list */ }
},
};
@@ -173,6 +180,7 @@ static QemuOptsList runtime_opts = {
#define PCACHE_DEFAULT_CACHE_SIZE (4 << MB_BITS)
#define PCACHE_DEFAULT_READAHEAD_SIZE (128 << KB_BITS)
#define PCACHE_DEFAULT_POOL_STAT_SIZE (1 << MB_BITS)
+#define PCACHE_DEFAULT_MAX_AIO_SIZE (32 << KB_BITS)
enum {
NODE_SUCCESS_STATUS = 0,
@@ -386,12 +394,7 @@ static void lreq_try_shrink(BDRVPCacheState *s)
{
while (s->lreq.curr_size > s->cfg.lreq_pool_size) {
LRNode *rmv_node;
- /* XXX: need to filter large requests */
- if (QTAILQ_EMPTY(&s->lreq.lru.list)) {
- DPRINTF("lru lreq list is empty, but curr_size: %d\n",
- s->lreq.curr_size);
- break;
- }
+ assert(!QTAILQ_EMPTY(&s->lreq.lru.list));
qemu_co_mutex_lock(&s->lreq.lru.lock);
rmv_node = LRNODE(QTAILQ_LAST(&s->lreq.lru.list, lru_head));
@@ -943,6 +946,23 @@ static void pcache_readahead_request(BlockDriverState *bs,
PrefCacheAIOCB *acb)
pcache_send_acb_request_list(bs, acb_readahead);
}
+static inline bool pcache_skip_aio_read(BlockDriverState *bs,
+ uint64_t sector_num,
+ uint32_t nb_sectors)
+{
+ BDRVPCacheState *s = bs->opaque;
+
+ if (nb_sectors > s->cfg.max_aio_size) {
+ return true;
+ }
+
+ if (bdrv_nb_sectors(bs) < sector_num + nb_sectors) {
+ return true;
+ }
+
+ return false;
+}
+
static BlockAIOCB *pcache_aio_readv(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
@@ -950,9 +970,16 @@ static BlockAIOCB *pcache_aio_readv(BlockDriverState *bs,
BlockCompletionFunc *cb,
void *opaque)
{
- PrefCacheAIOCB *acb = pcache_aio_get(bs, sector_num, qiov, nb_sectors, cb,
- opaque, PCACHE_AIO_READ);
- int32_t status = pcache_prefetch(acb);
+ PrefCacheAIOCB *acb;
+ int32_t status;
+
+ if (pcache_skip_aio_read(bs, sector_num, nb_sectors)) {
+ return bdrv_aio_readv(bs->file, sector_num, qiov, nb_sectors,
+ cb, opaque);
+ }
+ acb = pcache_aio_get(bs, sector_num, qiov, nb_sectors, cb,
+ opaque, PCACHE_AIO_READ);
+ status = pcache_prefetch(acb);
if (status == PREFETCH_NEW_NODE) {
BlockAIOCB *ret = bdrv_aio_readv(bs->file, sector_num, qiov,
nb_sectors,
cb, opaque);
@@ -993,9 +1020,12 @@ static void pcache_state_init(QemuOpts *opts,
BDRVPCacheState *s)
PCACHE_DEFAULT_CACHE_SIZE);
uint64_t readahead_size = qemu_opt_get_size(opts,
PCACHE_OPT_READAHEAD_SIZE,
PCACHE_DEFAULT_READAHEAD_SIZE);
+ uint64_t max_aio_size = qemu_opt_get_size(opts, PCACHE_OPT_MAX_AIO_SIZE,
+ PCACHE_DEFAULT_MAX_AIO_SIZE);
DPRINTF("pcache configure:\n");
DPRINTF("pcache-full-size = %jd\n", cache_size);
DPRINTF("readahead_size = %jd\n", readahead_size);
+ DPRINTF("max_aio_size = %jd\n", max_aio_size);
s->pcache.tree.root = RB_ROOT;
qemu_co_mutex_init(&s->pcache.tree.lock);
@@ -1012,6 +1042,7 @@ static void pcache_state_init(QemuOpts *opts,
BDRVPCacheState *s)
s->cfg.cache_size = cache_size >> BDRV_SECTOR_BITS;
s->cfg.readahead_size = readahead_size >> BDRV_SECTOR_BITS;
s->cfg.lreq_pool_size = PCACHE_DEFAULT_POOL_STAT_SIZE >> BDRV_SECTOR_BITS;
+ s->cfg.max_aio_size = max_aio_size >> BDRV_SECTOR_BITS;
#ifdef PCACHE_DEBUG
QTAILQ_INIT(&s->death_node_list);
--
2.8.3
- [Qemu-block] [PATCH RFC v2 00/22] I/O prefetch cache, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 15/22] block/pcache: simple readahead one chunk forward, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 06/22] block/pcache: restrict cache size, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 16/22] block/pcache: pcache readahead node around, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 08/22] block/pcache: implement pickup parts of the cache, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 18/22] block/pcache: add pcache skip large aio read,
Pavel Butsykin <=
- [Qemu-block] [PATCH RFC v2 09/22] block/pcache: separation AIOCB on requests, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 07/22] block/pcache: introduce LRU as method of memory, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 20/22] block/pcache: implement pcache error handling of aio cb, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 10/22] block/pcache: add check node leak, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 22/22] block/pcache: drop used pcache node, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 02/22] block/pcache: add own AIOCB block, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 14/22] block/pcache: add support for rescheduling requests, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 05/22] block/pcache: add aio requests into cache, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 04/22] block/pcache: add pcache debug build, Pavel Butsykin, 2016/08/29
- [Qemu-block] [PATCH RFC v2 17/22] block/pcache: skip readahead for non-sequential requests, Pavel Butsykin, 2016/08/29