Re: rq lock contention due to commit af7f588d8f73
From: Mathieu Desnoyers
Date: Tue Mar 28 2023 - 08:40:09 EST
On 2023-03-28 02:58, Aaron Lu wrote:
On Mon, Mar 27, 2023 at 03:57:43PM -0400, Mathieu Desnoyers wrote:
I've just resuscitated my per-runqueue concurrency ID cache patch from an older
patchset, and posted it as RFC. So far it passed one round of rseq selftests. Can
you test it in your environment to see if I'm on the right track ?
https://lore.kernel.org/lkml/20230327195318.137094-1-mathieu.desnoyers@xxxxxxxxxxxx/
There are improvements with this patch.
When running the client side sysbench with nr_thread=56, the lock contention
is gone%; with nr_thread=224(=nr_cpu of this machine), the lock contention
dropped from 75% to 27%.
This is a good start!
Can you compare this with Peter's approach to modify init/Kconfig, make
SCHED_MM_CID a bool, and set it =n in the kernel config ?
I just want to see what baseline we should compare against.
Another test we would want to try here: there is an arbitrary choice for
the runqueue cache array size in my own patch:
kernel/sched/sched.h:
# define RQ_CID_CACHE_SIZE 8
Can you try changing this value for 16 or 32 instead and see if it helps?
Thanks,
Mathieu
v6.3.0-rc4:
75.21% 75.20% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
37.30% native_queued_spin_lock_slowpath;_raw_spin_lock;__schedule;schedule;schedule_hrtimeout_range_clock;schedule_hrtimeout_range;do_sys_poll;__x64_sys_poll;do_syscall_64;entry_SYSCALL_64_after_hwframe;__poll;0x7f943d6fcff8;PQgetResult;0x7f943d6f9a2b;0x55c7f9bde88b
26.01% native_queued_spin_lock_slowpath;_raw_spin_lock;__schedule;schedule_idle;do_idle;cpu_startup_entry;start_secondary;secondary_startup_64_no_verify
11.36% native_queued_spin_lock_slowpath;_raw_spin_lock;__schedule;schedule;schedule_hrtimeout_range_clock;schedule_hrtimeout_range;do_epoll_wait;__x64_sys_epoll_wait;do_syscall_64;entry_SYSCALL_64_after_hwframe;epoll_wait;secure_read;0x55c4d1363867;pq_getbyte;PostgresMain;0x55c4d140c828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
v6.3.0-rc4+the_above_patch:
27.86% 27.85% [kernel.vmlinux] [k] native_queued_spin_lock_slowpath
7.31% native_queued_spin_lock_slowpath;_raw_spin_lock;try_to_wake_up;default_wake_function;pollwake;__wake_up_common;__wake_up_common_lock;__wake_up_sync_key;sock_def_readable;tcp_data_ready;tcp_rcv_established;tcp_v4_do_rcv;tcp_v4_rcv;ip_protocol_deliver_rcu;ip_local_deliver_finish;ip_local_deliver;ip_rcv;__netif_receive_skb_one_core;__netif_receive_skb;process_backlog;__napi_poll;net_rx_action;__do_softirq;do_softirq.part.0;__local_bh_enable_ip;ip_finish_output2;__ip_finish_output;ip_finish_output;ip_output;ip_local_out;__ip_queue_xmit;ip_queue_xmit;__tcp_transmit_skb;tcp_write_xmit;__tcp_push_pending_frames;tcp_push;tcp_sendmsg_locked;tcp_sendmsg;inet_sendmsg;sock_sendmsg;__sys_sendto;__x64_sys_sendto;do_syscall_64;entry_SYSCALL_64;__libc_send;0x5637a602e4cd;0x5637a602e98d;PostgresMain;0x5637a60d7828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
4.62% native_queued_spin_lock_slowpath;_raw_spin_lock;__schedule;schedule_idle;do_idle;cpu_startup_entry;start_secondary;secondary_startup_64_no_verify
4.20% native_queued_spin_lock_slowpath;_raw_spin_lock;__schedule;schedule;schedule_hrtimeout_range_clock;schedule_hrtimeout_range;do_epoll_wait;__x64_sys_epoll_wait;do_syscall_64;entry_SYSCALL_64;epoll_wait;secure_read;0x5637a602e867;pq_getbyte;PostgresMain;0x5637a60d7828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
1.66% native_queued_spin_lock_slowpath;_raw_spin_lock;raw_spin_rq_lock_nested;_raw_spin_rq_lock_irqsave;try_to_wake_up;default_wake_function;ep_autoremove_wake_function;__wake_up_common;__wake_up_common_lock;__wake_up;ep_poll_callback;__wake_up_common;__wake_up_common_lock;__wake_up_sync_key;sock_def_readable;tcp_data_ready;tcp_rcv_established;tcp_v4_do_rcv;tcp_v4_rcv;ip_protocol_deliver_rcu;ip_local_deliver_finish;ip_local_deliver;ip_rcv;__netif_receive_skb_one_core;__netif_receive_skb;process_backlog;__napi_poll;net_rx_action;__do_softirq;do_softirq.part.0;__local_bh_enable_ip;ip_finish_output2;__ip_finish_output;ip_finish_output;ip_output;ip_local_out;__ip_queue_xmit;ip_queue_xmit;__tcp_transmit_skb;tcp_write_xmit;__tcp_push_pending_frames;tcp_push;tcp_sendmsg_locked;tcp_sendmsg;inet_sendmsg;sock_sendmsg;__sys_sendto;__x64_sys_sendto;do_syscall_64;entry_SYSCALL_64;__libc_send
1.65% native_queued_spin_lock_slowpath;_raw_spin_lock;try_to_wake_up;default_wake_function;pollwake;__wake_up_common;__wake_up_common_lock;__wake_up_sync_key;sock_def_readable;tcp_data_ready;tcp_data_queue;tcp_rcv_established;tcp_v4_do_rcv;tcp_v4_rcv;ip_protocol_deliver_rcu;ip_local_deliver_finish;ip_local_deliver;ip_rcv;__netif_receive_skb_one_core;__netif_receive_skb;process_backlog;__napi_poll;net_rx_action;__do_softirq;do_softirq.part.0;__local_bh_enable_ip;ip_finish_output2;__ip_finish_output;ip_finish_output;ip_output;ip_local_out;__ip_queue_xmit;ip_queue_xmit;__tcp_transmit_skb;tcp_write_xmit;__tcp_push_pending_frames;tcp_push;tcp_sendmsg_locked;tcp_sendmsg;inet_sendmsg;sock_sendmsg;__sys_sendto;__x64_sys_sendto;do_syscall_64;entry_SYSCALL_64;__libc_send;0x5637a602e4cd;0x5637a602e69e;0x5637a602e7ae;0x5637a5e5f62e;standard_ExecutorRun;0x5637a615abeb;PortalRun;PostgresMain;0x5637a60d7828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
1.63% native_queued_spin_lock_slowpath;_raw_spin_lock;raw_spin_rq_lock_nested;__schedule;schedule;schedule_hrtimeout_range_clock;schedule_hrtimeout_range;do_epoll_wait;__x64_sys_epoll_wait;do_syscall_64;entry_SYSCALL_64;epoll_wait;secure_read;0x5637a602e867;pq_getbyte;PostgresMain;0x5637a60d7828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
1.40% native_queued_spin_lock_slowpath;_raw_spin_lock;raw_spin_rq_lock_nested;try_to_wake_up;default_wake_function;pollwake;__wake_up_common;__wake_up_common_lock;__wake_up_sync_key;sock_def_readable;tcp_data_ready;tcp_rcv_established;tcp_v4_do_rcv;tcp_v4_rcv;ip_protocol_deliver_rcu;ip_local_deliver_finish;ip_local_deliver;ip_rcv;__netif_receive_skb_one_core;__netif_receive_skb;process_backlog;__napi_poll;net_rx_action;__do_softirq;do_softirq.part.0;__local_bh_enable_ip;ip_finish_output2;__ip_finish_output;ip_finish_output;ip_output;ip_local_out;__ip_queue_xmit;ip_queue_xmit;__tcp_transmit_skb;tcp_write_xmit;__tcp_push_pending_frames;tcp_push;tcp_sendmsg_locked;tcp_sendmsg;inet_sendmsg;sock_sendmsg;__sys_sendto;__x64_sys_sendto;do_syscall_64;entry_SYSCALL_64;__libc_send;0x5637a602e4cd;0x5637a602e98d;PostgresMain;0x5637a60d7828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
1.20% native_queued_spin_lock_slowpath;_raw_spin_lock;raw_spin_rq_lock_nested;_raw_spin_rq_lock_irqsave;try_to_wake_up;default_wake_function;pollwake;__wake_up_common;__wake_up_common_lock;__wake_up_sync_key;sock_def_readable;tcp_data_ready;tcp_rcv_established;tcp_v4_do_rcv;tcp_v4_rcv;ip_protocol_deliver_rcu;ip_local_deliver_finish;ip_local_deliver;ip_rcv;__netif_receive_skb_one_core;__netif_receive_skb;process_backlog;__napi_poll;net_rx_action;__do_softirq;do_softirq.part.0;__local_bh_enable_ip;ip_finish_output2;__ip_finish_output;ip_finish_output;ip_output;ip_local_out;__ip_queue_xmit;ip_queue_xmit;__tcp_transmit_skb;tcp_write_xmit;__tcp_push_pending_frames;tcp_push;tcp_sendmsg_locked;tcp_sendmsg;inet_sendmsg;sock_sendmsg;__sys_sendto;__x64_sys_sendto;do_syscall_64;entry_SYSCALL_64;__libc_send;0x5637a602e4cd;0x5637a602e98d;PostgresMain;0x5637a60d7828;PostmasterMain;main;__libc_start_main;0x5541d68949564100
0.83% native_queued_spin_lock_slowpath;_raw_spin_lock;raw_spin_rq_lock_nested;__task_rq_lock;try_to_wake_up;default_wake_function;ep_autoremove_wake_function;__wake_up_common;__wake_up_common_lock;__wake_up;ep_poll_callback;__wake_up_common;__wake_up_common_lock;__wake_up_sync_key;sock_def_readable;tcp_data_ready;tcp_rcv_established;tcp_v4_do_rcv;tcp_v4_rcv;ip_protocol_deliver_rcu;ip_local_deliver_finish;ip_local_deliver;ip_rcv;__netif_receive_skb_one_core;__netif_receive_skb;process_backlog;__napi_poll;net_rx_action;__do_softirq;do_softirq.part.0;__local_bh_enable_ip;ip_finish_output2;__ip_finish_output;ip_finish_output;ip_output;ip_local_out;__ip_queue_xmit;ip_queue_xmit;__tcp_transmit_skb;tcp_write_xmit;__tcp_push_pending_frames;tcp_push;tcp_sendmsg_locked;tcp_sendmsg;inet_sendmsg;sock_sendmsg;__sys_sendto;__x64_sys_sendto;do_syscall_64;entry_SYSCALL_64;__libc_send
0.65% native_queued_spin_lock_slowpath;_raw_spin_lock;raw_spin_rq_lock_nested;__schedule;schedule_idle;do_idle;cpu_startup_entry;start_secondary;secondary_startup_64_no_verify
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com