From 4a07723fb4bb2568a31d43709904ab0d4c33d6c8 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 16 Jun 2022 10:22:05 +0100 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/b9620c8072ba61a2d50eba894b89bd93a94a9abd.1655371007.git.asml.silence@gmail.com Reviewed-by: Hao Xu Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index ac6946e3f174..aafdf1330ec6 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), -- GitLab