On 20.09.19 г. 18:15 ч., Steven Rostedt wrote:
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> When loading a data file that contained 100,000s of tasks, using a 256 bucket size hash crippled it. By increasing the hash to 2^16 (65536) it solves the issue (still small enough not to waste too much memory). Also switched to the tracecmd_quick_hash() which is basically the same as the local knuth_hash() function in libkshark.c. Link: http://lore.kernel.org/linux-trace-devel/20190828140016.3ce1be4f@xxxxxxxxxxxxxxxxxx Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- kernel-shark/src/libkshark.c | 18 ++++-------------- kernel-shark/src/libkshark.h | 3 ++- 2 files changed, 6 insertions(+), 15 deletions(-) diff --git a/kernel-shark/src/libkshark.c b/kernel-shark/src/libkshark.c index 4207ae6ffdb2..a36157835ce0 100644 --- a/kernel-shark/src/libkshark.c +++ b/kernel-shark/src/libkshark.c @@ -252,19 +252,8 @@ void kshark_free(struct kshark_context *kshark_ctx) free(kshark_ctx); }-static inline uint8_t knuth_hash(uint32_t val)-{ - /* - * Small table hashing function adapted from Donald E. Knuth's 32 bit - * multiplicative hash. See The Art of Computer Programming (TAOCP). - * Multiplication by the Prime number, closest to the golden ratio of - * 2^8. - */ - return UINT8_C(val) * UINT8_C(157); -} - static struct kshark_task_list * -kshark_find_task(struct kshark_context *kshark_ctx, uint8_t key, int pid) +kshark_find_task(struct kshark_context *kshark_ctx, uint32_t key, int pid) { struct kshark_task_list *list;@@ -280,9 +269,10 @@ static struct kshark_task_list *kshark_add_task(struct kshark_context *kshark_ctx, int pid) { struct kshark_task_list *list; - uint8_t key; + uint32_t key; + + key = tracecmd_quick_hash(pid, KS_TASK_HASH_SHIFT);- key = knuth_hash(pid);list = kshark_find_task(kshark_ctx, key, pid); if (list) return list; diff --git a/kernel-shark/src/libkshark.h b/kernel-shark/src/libkshark.h index 04e9cbfc71df..3407db197320 100644 --- a/kernel-shark/src/libkshark.h +++ b/kernel-shark/src/libkshark.h @@ -72,7 +72,8 @@ struct kshark_entry { };/** Size of the task's hash table. */-#define KS_TASK_HASH_SIZE 256 +#define KS_TASK_HASH_SHIFT 16 +#define KS_TASK_HASH_SIZE (1 << KS_TASK_HASH_SHIFT)/** Linked list of tasks. */struct kshark_task_list {
Both patches look good to me. Thanks! Reviewed-by: Yordan Karadzhov (VMware) <y.karadz@xxxxxxxxx>
|