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io_uring: optimise SQPOLL mm/files grabbing 

There are two reasons for this. First is to optimise
io_sq_thread_acquire_mm_files() for non-SQPOLL case, which currently do
too many checks and function calls in the hot path, e.g. in
io_init_req().

The second is to not grab mm/files when there are not needed. As
__io_queue_sqe() issues only one request now, we can reuse
io_sq_thread_acquire_mm_files() instead of unconditional acquire
mm/files.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-02-12 03:23:52 +00:00 committed by Jens Axboe
parent d3d7298d05
commit 4e32635834
1 changed files with 13 additions and 14 deletions
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27
fs/io_uring.c
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@ -1145,9 +1145,6 @@ static void io_sq_thread_drop_mm_files(void)
static int __io_sq_thread_acquire_files(struct io_ring_ctx *ctx)
{
if (current->flags & PF_EXITING)
return -EFAULT;
if (!current->files) {
struct files_struct *files;
struct nsproxy *nsproxy;
@ -1175,15 +1172,9 @@ static int __io_sq_thread_acquire_mm(struct io_ring_ctx *ctx)
{
struct mm_struct *mm;
if (current->flags & PF_EXITING)
return -EFAULT;
if (current->mm)
return 0;
/* Should never happen */
if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL)))
return -EFAULT;
task_lock(ctx->sqo_task);
mm = ctx->sqo_task->mm;
if (unlikely(!mm || !mmget_not_zero(mm)))
@ -1198,8 +1189,8 @@ static int __io_sq_thread_acquire_mm(struct io_ring_ctx *ctx)
return -EFAULT;
}
static int io_sq_thread_acquire_mm_files(struct io_ring_ctx *ctx,
struct io_kiocb *req)
static int __io_sq_thread_acquire_mm_files(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
const struct io_op_def *def = &io_op_defs[req->opcode];
int ret;
@ -1219,6 +1210,16 @@ static int io_sq_thread_acquire_mm_files(struct io_ring_ctx *ctx,
return 0;
}
static inline int io_sq_thread_acquire_mm_files(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
if (unlikely(current->flags & PF_EXITING))
return -EFAULT;
if (!(ctx->flags & IORING_SETUP_SQPOLL))
return 0;
return __io_sq_thread_acquire_mm_files(ctx, req);
}
static void io_sq_thread_associate_blkcg(struct io_ring_ctx *ctx,
struct cgroup_subsys_state **cur_css)
@ -2336,9 +2337,7 @@ static void __io_req_task_submit(struct io_kiocb *req)
struct io_ring_ctx *ctx = req->ctx;
mutex_lock(&ctx->uring_lock);
if (!ctx->sqo_dead &&
!__io_sq_thread_acquire_mm(ctx) &&
!__io_sq_thread_acquire_files(ctx))
if (!ctx->sqo_dead && !io_sq_thread_acquire_mm_files(ctx, req))
__io_queue_sqe(req);
else
__io_req_task_cancel(req, -EFAULT);