* [PATCH 1/2] io_uring: optimise io_req_set_rsrc_node()
2021-10-09 22:14 [PATCH 0/2] yet another optimisation for-next Pavel Begunkov
@ 2021-10-09 22:14 ` Pavel Begunkov
2021-10-09 22:14 ` [PATCH 2/2] io_uring: optimise ctx referencing Pavel Begunkov
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Pavel Begunkov @ 2021-10-09 22:14 UTC (permalink / raw)
To: io-uring; +Cc: Jens Axboe, asml.silence
io_req_set_rsrc_node() reloads loads req->ctx, however it's already in
registers in all use cases, so better to pass it as a parameter.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index dff732397264..24984b3f4a49 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1175,10 +1175,9 @@ static inline void io_req_set_refcount(struct io_kiocb *req)
__io_req_set_refcount(req, 1);
}
-static inline void io_req_set_rsrc_node(struct io_kiocb *req)
+static inline void io_req_set_rsrc_node(struct io_kiocb *req,
+ struct io_ring_ctx *ctx)
{
- struct io_ring_ctx *ctx = req->ctx;
-
if (!req->fixed_rsrc_refs) {
req->fixed_rsrc_refs = &ctx->rsrc_node->refs;
percpu_ref_get(req->fixed_rsrc_refs);
@@ -2843,7 +2842,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
if (req->opcode == IORING_OP_READ_FIXED ||
req->opcode == IORING_OP_WRITE_FIXED) {
req->imu = NULL;
- io_req_set_rsrc_node(req);
+ io_req_set_rsrc_node(req, ctx);
}
req->rw.addr = READ_ONCE(sqe->addr);
@@ -6772,7 +6771,7 @@ static inline struct file *io_file_get_fixed(struct io_ring_ctx *ctx,
file_ptr &= ~FFS_MASK;
/* mask in overlapping REQ_F and FFS bits */
req->flags |= (file_ptr << REQ_F_NOWAIT_READ_BIT);
- io_req_set_rsrc_node(req);
+ io_req_set_rsrc_node(req, ctx);
return file;
}
--
2.33.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH 2/2] io_uring: optimise ctx referencing
2021-10-09 22:14 [PATCH 0/2] yet another optimisation for-next Pavel Begunkov
2021-10-09 22:14 ` [PATCH 1/2] io_uring: optimise io_req_set_rsrc_node() Pavel Begunkov
@ 2021-10-09 22:14 ` Pavel Begunkov
2021-10-14 13:50 ` (subset) [PATCH 0/2] yet another optimisation for-next Jens Axboe
2021-10-14 13:54 ` Jens Axboe
3 siblings, 0 replies; 5+ messages in thread
From: Pavel Begunkov @ 2021-10-09 22:14 UTC (permalink / raw)
To: io-uring; +Cc: Jens Axboe, asml.silence
Apparently, percpu_ref_put/get() are expensive enough if done per
request, get them in a batch and cache on the submission side to avoid
getting it over and over again. Also, if we're completing under
uring_lock, return refs back into the cache instead of
perfcpu_ref_put(). Pretty similar to how we do tctx->cached_refs
accounting, but fall back to normal putting when we already changed a
rsrc node by the time of free.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 49 insertions(+), 3 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 24984b3f4a49..e558a68a371d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -361,6 +361,7 @@ struct io_ring_ctx {
* uring_lock, and updated through io_uring_register(2)
*/
struct io_rsrc_node *rsrc_node;
+ int rsrc_cached_refs;
struct io_file_table file_table;
unsigned nr_user_files;
unsigned nr_user_bufs;
@@ -1175,12 +1176,52 @@ static inline void io_req_set_refcount(struct io_kiocb *req)
__io_req_set_refcount(req, 1);
}
+#define IO_RSRC_REF_BATCH 100
+
+static inline void io_req_put_rsrc_locked(struct io_kiocb *req,
+ struct io_ring_ctx *ctx)
+ __must_hold(&ctx->uring_lock)
+{
+ struct percpu_ref *ref = req->fixed_rsrc_refs;
+
+ if (ref) {
+ if (ref == &ctx->rsrc_node->refs)
+ ctx->rsrc_cached_refs++;
+ else
+ percpu_ref_put(ref);
+ }
+}
+
+static inline void io_req_put_rsrc(struct io_kiocb *req, struct io_ring_ctx *ctx)
+{
+ if (req->fixed_rsrc_refs)
+ percpu_ref_put(req->fixed_rsrc_refs);
+}
+
+static __cold void io_rsrc_refs_drop(struct io_ring_ctx *ctx)
+ __must_hold(&ctx->uring_lock)
+{
+ if (ctx->rsrc_cached_refs) {
+ percpu_ref_put_many(&ctx->rsrc_node->refs, ctx->rsrc_cached_refs);
+ ctx->rsrc_cached_refs = 0;
+ }
+}
+
+static void io_rsrc_refs_refill(struct io_ring_ctx *ctx)
+ __must_hold(&ctx->uring_lock)
+{
+ ctx->rsrc_cached_refs += IO_RSRC_REF_BATCH;
+ percpu_ref_get_many(&ctx->rsrc_node->refs, IO_RSRC_REF_BATCH);
+}
+
static inline void io_req_set_rsrc_node(struct io_kiocb *req,
struct io_ring_ctx *ctx)
{
if (!req->fixed_rsrc_refs) {
req->fixed_rsrc_refs = &ctx->rsrc_node->refs;
- percpu_ref_get(req->fixed_rsrc_refs);
+ ctx->rsrc_cached_refs--;
+ if (unlikely(ctx->rsrc_cached_refs < 0))
+ io_rsrc_refs_refill(ctx);
}
}
@@ -1801,6 +1842,7 @@ static void io_req_complete_post(struct io_kiocb *req, s32 res,
req->link = NULL;
}
}
+ io_req_put_rsrc(req, ctx);
io_dismantle_req(req);
io_put_task(req->task, 1);
wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
@@ -1957,14 +1999,13 @@ static inline void io_dismantle_req(struct io_kiocb *req)
io_clean_op(req);
if (!(flags & REQ_F_FIXED_FILE))
io_put_file(req->file);
- if (req->fixed_rsrc_refs)
- percpu_ref_put(req->fixed_rsrc_refs);
}
static __cold void __io_free_req(struct io_kiocb *req)
{
struct io_ring_ctx *ctx = req->ctx;
+ io_req_put_rsrc(req, ctx);
io_dismantle_req(req);
io_put_task(req->task, 1);
@@ -2271,6 +2312,7 @@ static void io_free_batch_list(struct io_ring_ctx *ctx,
continue;
}
+ io_req_put_rsrc_locked(req, ctx);
io_queue_next(req);
io_dismantle_req(req);
@@ -7646,10 +7688,13 @@ static struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx)
static void io_rsrc_node_switch(struct io_ring_ctx *ctx,
struct io_rsrc_data *data_to_kill)
+ __must_hold(&ctx->uring_lock)
{
WARN_ON_ONCE(!ctx->rsrc_backup_node);
WARN_ON_ONCE(data_to_kill && !ctx->rsrc_node);
+ io_rsrc_refs_drop(ctx);
+
if (data_to_kill) {
struct io_rsrc_node *rsrc_node = ctx->rsrc_node;
@@ -9203,6 +9248,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
ctx->mm_account = NULL;
}
+ io_rsrc_refs_drop(ctx);
/* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
io_wait_rsrc_data(ctx->buf_data);
io_wait_rsrc_data(ctx->file_data);
--
2.33.0
^ permalink raw reply related [flat|nested] 5+ messages in thread