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io_uring: enable req cache for IRQ driven IO 

This is the last class of requests that cannot utilize the req alloc
cache. Add a per-ctx req cache that is protected by the completion_lock,
and refill our submit side cache when it gets over our batch count.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-02-09 19:53:37 -07:00
parent ed670c3f90
commit c7dae4ba46
1 changed files with 51 additions and 20 deletions
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71
fs/io_uring.c
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@ -272,7 +272,11 @@ struct io_sq_data {
struct io_comp_state {
struct io_kiocb *reqs[IO_COMPL_BATCH];
unsigned int nr;
unsigned int locked_free_nr;
/* inline/task_work completion list, under ->uring_lock */
struct list_head free_list;
/* IRQ completion list, under ->completion_lock */
struct list_head locked_free_list;
};
struct io_submit_state {
@ -1033,6 +1037,9 @@ static void io_cqring_fill_event(struct io_kiocb *req, long res);
static void io_put_req(struct io_kiocb *req);
static void io_put_req_deferred(struct io_kiocb *req, int nr);
static void io_double_put_req(struct io_kiocb *req);
static void io_dismantle_req(struct io_kiocb *req);
static void io_put_task(struct task_struct *task, int nr);
static void io_queue_next(struct io_kiocb *req);
static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req);
static void __io_queue_linked_timeout(struct io_kiocb *req);
static void io_queue_linked_timeout(struct io_kiocb *req);
@ -1353,6 +1360,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
INIT_DELAYED_WORK(&ctx->rsrc_put_work, io_rsrc_put_work);
init_llist_head(&ctx->rsrc_put_llist);
INIT_LIST_HEAD(&ctx->submit_state.comp.free_list);
INIT_LIST_HEAD(&ctx->submit_state.comp.locked_free_list);
return ctx;
err:
kfree(ctx->cancel_hash);
@ -1908,8 +1916,8 @@ static void io_cqring_fill_event(struct io_kiocb *req, long res)
__io_cqring_fill_event(req, res, 0);
}
static void io_req_complete_post(struct io_kiocb *req, long res,
unsigned int cflags)
static inline void io_req_complete_post(struct io_kiocb *req, long res,
unsigned int cflags)
{
struct io_ring_ctx *ctx = req->ctx;
unsigned long flags;
@ -1917,16 +1925,26 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
spin_lock_irqsave(&ctx->completion_lock, flags);
__io_cqring_fill_event(req, res, cflags);
io_commit_cqring(ctx);
/*
* If we're the last reference to this request, add to our locked
* free_list cache.
*/
if (refcount_dec_and_test(&req->refs)) {
struct io_comp_state *cs = &ctx->submit_state.comp;
io_dismantle_req(req);
io_put_task(req->task, 1);
list_add(&req->compl.list, &cs->locked_free_list);
cs->locked_free_nr++;
} else
req = NULL;
spin_unlock_irqrestore(&ctx->completion_lock, flags);
io_cqring_ev_posted(ctx);
}
static inline void io_req_complete_nostate(struct io_kiocb *req, long res,
unsigned int cflags)
{
io_req_complete_post(req, res, cflags);
io_put_req(req);
if (req) {
io_queue_next(req);
percpu_ref_put(&ctx->refs);
}
}
static void io_req_complete_state(struct io_kiocb *req, long res,
@ -1944,7 +1962,7 @@ static inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags,
if (issue_flags & IO_URING_F_COMPLETE_DEFER)
io_req_complete_state(req, res, cflags);
else
io_req_complete_nostate(req, res, cflags);
io_req_complete_post(req, res, cflags);
}
static inline void io_req_complete(struct io_kiocb *req, long res)
@ -1952,12 +1970,26 @@ static inline void io_req_complete(struct io_kiocb *req, long res)
__io_req_complete(req, 0, res, 0);
}
static bool io_flush_cached_reqs(struct io_submit_state *state)
static bool io_flush_cached_reqs(struct io_ring_ctx *ctx)
{
struct io_submit_state *state = &ctx->submit_state;
struct io_comp_state *cs = &state->comp;
struct io_kiocb *req = NULL;
while (!list_empty(&state->comp.free_list)) {
req = list_first_entry(&state->comp.free_list, struct io_kiocb,
/*
* If we have more than a batch's worth of requests in our IRQ side
* locked cache, grab the lock and move them over to our submission
* side cache.
*/
if (READ_ONCE(cs->locked_free_nr) > IO_COMPL_BATCH) {
spin_lock_irq(&ctx->completion_lock);
list_splice_init(&cs->locked_free_list, &cs->free_list);
cs->locked_free_nr = 0;
spin_unlock_irq(&ctx->completion_lock);
}
while (!list_empty(&cs->free_list)) {
req = list_first_entry(&cs->free_list, struct io_kiocb,
compl.list);
list_del(&req->compl.list);
state->reqs[state->free_reqs++] = req;
@ -1978,7 +2010,7 @@ static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx)
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
int ret;
if (io_flush_cached_reqs(state))
if (io_flush_cached_reqs(ctx))
goto got_req;
ret = kmem_cache_alloc_bulk(req_cachep, gfp, IO_REQ_ALLOC_BATCH,
@ -8748,14 +8780,12 @@ static void io_destroy_buffers(struct io_ring_ctx *ctx)
idr_destroy(&ctx->io_buffer_idr);
}
static void io_req_cache_free(struct io_ring_ctx *ctx)
static void io_req_cache_free(struct list_head *list)
{
struct io_comp_state *cs = &ctx->submit_state.comp;
while (!list_empty(&cs->free_list)) {
while (!list_empty(list)) {
struct io_kiocb *req;
req = list_first_entry(&cs->free_list, struct io_kiocb, compl.list);
req = list_first_entry(list, struct io_kiocb, compl.list);
list_del(&req->compl.list);
kmem_cache_free(req_cachep, req);
}
@ -8803,7 +8833,8 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
free_uid(ctx->user);
put_cred(ctx->creds);
kfree(ctx->cancel_hash);
io_req_cache_free(ctx);
io_req_cache_free(&ctx->submit_state.comp.free_list);
io_req_cache_free(&ctx->submit_state.comp.locked_free_list);
kfree(ctx);
}