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authorPavel Begunkov <asml.silence@gmail.com>2022-06-16 10:22:05 +0100
committerJens Axboe <axboe@kernel.dk>2022-06-22 11:31:22 -0600
commit929889cf665533b05459cf9f308724878a5c2a3b (patch)
treef0365ba84b97eccb03c2b38996c0690f0e8e22f0
parent1250d3574051a0f69406b5173586f162395bbeec (diff)
io_uring: limit the number of cancellation buckets
Don't allocate to many hash/cancellation buckets, there might be too many, clamp it to 8 bits, or 256 * 64B = 16KB. We don't usually have too many requests, and 256 buckets should be enough, especially since we do hash search only in the cancellation path. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/b9620c8072ba61a2d50eba894b89bd93a94a9abd.1655371007.git.asml.silence@gmail.com Reviewed-by: Hao Xu <howeyxu@tencent.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--io_uring/io_uring.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index eab5953038c0..fe6bd48db688 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -254,12 +254,12 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
/*
* Use 5 bits less than the max cq entries, that should give us around
- * 32 entries per hash list if totally full and uniformly spread.
+ * 32 entries per hash list if totally full and uniformly spread, but
+ * don't keep too many buckets to not overconsume memory.
*/
- hash_bits = ilog2(p->cq_entries);
- hash_bits -= 5;
- if (hash_bits <= 0)
- hash_bits = 1;
+ hash_bits = ilog2(p->cq_entries) - 5;
+ hash_bits = clamp(hash_bits, 1, 8);
+
ctx->cancel_hash_bits = hash_bits;
ctx->cancel_hash =
kmalloc((1U << hash_bits) * sizeof(struct io_hash_bucket),