From b7b78c1c169dd2213b4cb3e14e19c045b2c5e5af Mon Sep 17 00:00:00 2001 From: Randall Stewart Date: Thu, 28 Mar 2024 08:12:37 -0400 Subject: [PATCH] Optimize HPTS so that little work is done until we have a hpts thread that is over the connection threshold HPTS inserts a softclock for system call return that optimizes performance. However when no HPTS threads need the help (i.e. when they have less than 100 or so connections) then there should be little work done i.e. check the counter and return instead of running through all the threads getting locks etc.ptimize HPTS so that little work is done until we have a hpts thread that is over the connection threshold. Reported by: eduardo Reviewed by: gallatin, glebius, tuexen Tested by: gallatin Differential Revision: https://reviews.freebsd.org/D44420 --- sys/kern/subr_trap.c | 2 ++ sys/netinet/tcp_hpts.c | 10 +++++++++- sys/sys/systm.h | 4 +++- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/sys/kern/subr_trap.c b/sys/kern/subr_trap.c index e9a16cd0b36..18388ae5f23 100644 --- a/sys/kern/subr_trap.c +++ b/sys/kern/subr_trap.c @@ -74,6 +74,8 @@ #include #endif +volatile uint32_t __read_frequently hpts_that_need_softclock = 0; + void (*tcp_hpts_softclock)(void); /* diff --git a/sys/netinet/tcp_hpts.c b/sys/netinet/tcp_hpts.c index 8c4d2d41a3e..222f8e0229d 100644 --- a/sys/netinet/tcp_hpts.c +++ b/sys/netinet/tcp_hpts.c @@ -193,7 +193,8 @@ struct tcp_hpts_entry { uint8_t p_direct_wake :1, /* boolean */ p_on_min_sleep:1, /* boolean */ p_hpts_wake_scheduled:1, /* boolean */ - p_avail:5; + hit_callout_thresh:1, + p_avail:4; uint8_t p_fill[3]; /* Fill to 32 bits */ /* Cache line 0x40 */ struct hptsh { @@ -1683,6 +1684,13 @@ tcp_hpts_thread(void *ctx) ticks_ran = tcp_hptsi(hpts, 1); tv.tv_sec = 0; tv.tv_usec = hpts->p_hpts_sleep_time * HPTS_TICKS_PER_SLOT; + if ((hpts->p_on_queue_cnt > conn_cnt_thresh) && (hpts->hit_callout_thresh == 0)) { + hpts->hit_callout_thresh = 1; + atomic_add_int(&hpts_that_need_softclock, 1); + } else if ((hpts->p_on_queue_cnt <= conn_cnt_thresh) && (hpts->hit_callout_thresh == 1)) { + hpts->hit_callout_thresh = 0; + atomic_subtract_int(&hpts_that_need_softclock, 1); + } if (hpts->p_on_queue_cnt >= conn_cnt_thresh) { if(hpts->p_direct_wake == 0) { /* diff --git a/sys/sys/systm.h b/sys/sys/systm.h index 435e6b61c90..6c2b466c4cf 100644 --- a/sys/sys/systm.h +++ b/sys/sys/systm.h @@ -400,8 +400,10 @@ extern int cpu_disable_c2_sleep; extern int cpu_disable_c3_sleep; extern void (*tcp_hpts_softclock)(void); +extern volatile uint32_t __read_frequently hpts_that_need_softclock; + #define tcp_hpts_softclock() do { \ - if (tcp_hpts_softclock != NULL) \ + if (hpts_that_need_softclock > 0) \ tcp_hpts_softclock(); \ } while (0)