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io_uring/napi: add static napi tracking strategy

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Add the static napi tracking strategy. That allows the user to manually
manage the napi ids list for busy polling, and eliminate the overhead of
dynamically updating the list from the fast path.

Signed-off-by: Olivier Langlois <olivier@trillion01.com>
Link: https://lore.kernel.org/r/96943de14968c35a5c599352259ad98f3c0770ba.1728828877.git.olivier@trillion01.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Olivier Langlois
2024-10-13 14:29:24 -04:00
committed by Jens Axboe
parent 71afd926f2
commit 6bf90bd8c5
5 changed files with 160 additions and 27 deletions
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97
io_uring/napi.c
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@@ -81,6 +81,27 @@ int __io_napi_add_id(struct io_ring_ctx *ctx, unsigned int napi_id)
return 0;
}
static int __io_napi_del_id(struct io_ring_ctx *ctx, unsigned int napi_id)
{
struct hlist_head *hash_list;
struct io_napi_entry *e;
/* Non-NAPI IDs can be rejected. */
if (napi_id < MIN_NAPI_ID)
return -EINVAL;
hash_list = &ctx->napi_ht[hash_min(napi_id, HASH_BITS(ctx->napi_ht))];
guard(spinlock)(&ctx->napi_lock);
e = io_napi_hash_find(hash_list, napi_id);
if (!e)
return -ENOENT;
list_del_rcu(&e->list);
hash_del_rcu(&e->node);
kfree_rcu(e, rcu);
return 0;
}
static void __io_napi_remove_stale(struct io_ring_ctx *ctx)
{
struct io_napi_entry *e;
@@ -136,9 +157,25 @@ static bool io_napi_busy_loop_should_end(void *data,
return false;
}
static bool __io_napi_do_busy_loop(struct io_ring_ctx *ctx,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg)
/*
* never report stale entries
*/
static bool static_tracking_do_busy_loop(struct io_ring_ctx *ctx,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg)
{
struct io_napi_entry *e;
list_for_each_entry_rcu(e, &ctx->napi_list, list)
napi_busy_loop_rcu(e->napi_id, loop_end, loop_end_arg,
ctx->napi_prefer_busy_poll, BUSY_POLL_BUDGET);
return false;
}
static bool
dynamic_tracking_do_busy_loop(struct io_ring_ctx *ctx,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg)
{
struct io_napi_entry *e;
bool is_stale = false;
@@ -154,6 +191,16 @@ static bool __io_napi_do_busy_loop(struct io_ring_ctx *ctx,
return is_stale;
}
static inline bool
__io_napi_do_busy_loop(struct io_ring_ctx *ctx,
bool (*loop_end)(void *, unsigned long),
void *loop_end_arg)
{
if (READ_ONCE(ctx->napi_track_mode) == IO_URING_NAPI_TRACKING_STATIC)
return static_tracking_do_busy_loop(ctx, loop_end, loop_end_arg);
return dynamic_tracking_do_busy_loop(ctx, loop_end, loop_end_arg);
}
static void io_napi_blocking_busy_loop(struct io_ring_ctx *ctx,
struct io_wait_queue *iowq)
{
@@ -195,6 +242,7 @@ void io_napi_init(struct io_ring_ctx *ctx)
spin_lock_init(&ctx->napi_lock);
ctx->napi_prefer_busy_poll = false;
ctx->napi_busy_poll_dt = ns_to_ktime(sys_dt);
ctx->napi_track_mode = IO_URING_NAPI_TRACKING_INACTIVE;
}
/*
@@ -215,6 +263,24 @@ void io_napi_free(struct io_ring_ctx *ctx)
INIT_LIST_HEAD_RCU(&ctx->napi_list);
}
static int io_napi_register_napi(struct io_ring_ctx *ctx,
struct io_uring_napi *napi)
{
switch (napi->op_param) {
case IO_URING_NAPI_TRACKING_DYNAMIC:
case IO_URING_NAPI_TRACKING_STATIC:
break;
default:
return -EINVAL;
}
/* clean the napi list for new settings */
io_napi_free(ctx);
WRITE_ONCE(ctx->napi_track_mode, napi->op_param);
WRITE_ONCE(ctx->napi_busy_poll_dt, napi->busy_poll_to * NSEC_PER_USEC);
WRITE_ONCE(ctx->napi_prefer_busy_poll, !!napi->prefer_busy_poll);
return 0;
}
/*
* io_napi_register() - Register napi with io-uring
* @ctx: pointer to io-uring context structure
@@ -226,7 +292,8 @@ int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
{
const struct io_uring_napi curr = {
.busy_poll_to = ktime_to_us(ctx->napi_busy_poll_dt),
.prefer_busy_poll = ctx->napi_prefer_busy_poll
.prefer_busy_poll = ctx->napi_prefer_busy_poll,
.op_param = ctx->napi_track_mode
};
struct io_uring_napi napi;
@@ -234,16 +301,26 @@ int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
return -EINVAL;
if (copy_from_user(&napi, arg, sizeof(napi)))
return -EFAULT;
if (napi.pad[0] || napi.pad[1] || napi.pad[2] || napi.resv)
if (napi.pad[0] || napi.pad[1] || napi.resv)
return -EINVAL;
if (copy_to_user(arg, &curr, sizeof(curr)))
return -EFAULT;
WRITE_ONCE(ctx->napi_busy_poll_dt, napi.busy_poll_to * NSEC_PER_USEC);
WRITE_ONCE(ctx->napi_prefer_busy_poll, !!napi.prefer_busy_poll);
WRITE_ONCE(ctx->napi_enabled, true);
return 0;
switch (napi.opcode) {
case IO_URING_NAPI_REGISTER_OP:
return io_napi_register_napi(ctx, &napi);
case IO_URING_NAPI_STATIC_ADD_ID:
if (curr.op_param != IO_URING_NAPI_TRACKING_STATIC)
return -EINVAL;
return __io_napi_add_id(ctx, napi.op_param);
case IO_URING_NAPI_STATIC_DEL_ID:
if (curr.op_param != IO_URING_NAPI_TRACKING_STATIC)
return -EINVAL;
return __io_napi_del_id(ctx, napi.op_param);
default:
return -EINVAL;
}
}
/*
@@ -266,7 +343,7 @@ int io_unregister_napi(struct io_ring_ctx *ctx, void __user *arg)
WRITE_ONCE(ctx->napi_busy_poll_dt, 0);
WRITE_ONCE(ctx->napi_prefer_busy_poll, false);
WRITE_ONCE(ctx->napi_enabled, false);
WRITE_ONCE(ctx->napi_track_mode, IO_URING_NAPI_TRACKING_INACTIVE);
return 0;
}