Messages in this thread | | | Date | Fri, 26 Aug 2022 16:58:48 +0800 | Subject | Re: [External] Re: [PATCH v2] iommu/iova: Optimize alloc_iova with rbtree_augmented | From | Ethan Zhao <> |
| |
Peng,
在 2022/8/25 16:10, Peng Zhang 写道: > > Hi, > > Here is a real example. The version of kernel is 5.4.56. > Occurs when a lot of iova are not released for a long time. > > [Wed May 25 05:27:59 2022] watchdog: BUG: soft lockup - CPU#58 stuck > for 23s! [ksoftirqd/58:302] > [Wed May 25 05:27:59 2022] Call Trace: > [Wed May 25 05:27:59 2022] alloc_iova+0xf2/0x140 > [Wed May 25 05:27:59 2022] alloc_iova_fast+0x56/0x251 The rcache doesn't work at all , the worst case. > [Wed May 25 05:27:59 2022] dma_ops_alloc_iova.isra.27+0x4b/0x70 > [Wed May 25 05:27:59 2022] __map_single.isra.28+0x4a/0x1d0 > [Wed May 25 05:27:59 2022] mlx5e_sq_xmit+0x98d/0x12b0 [mlx5_core] > [Wed May 25 05:27:59 2022] ? packet_rcv+0x43/0x460 > [Wed May 25 05:27:59 2022] ? dev_hard_start_xmit+0x90/0x1e0 > [Wed May 25 05:27:59 2022] ? sch_direct_xmit+0x111/0x320 > [Wed May 25 05:27:59 2022] ? __qdisc_run+0x143/0x540 > [Wed May 25 05:27:59 2022] ? __dev_queue_xmit+0x6c3/0x8e0 > [Wed May 25 05:27:59 2022] ? ip_finish_output2+0x2d5/0x580 > [Wed May 25 05:27:59 2022] ? __ip_finish_output+0xe9/0x1b0 > [Wed May 25 05:27:59 2022] ? ip_output+0x6c/0xe0 > [Wed May 25 05:27:59 2022] ? __ip_finish_output+0x1b0/0x1b0 > [Wed May 25 05:27:59 2022] ? __ip_queue_xmit+0x15d/0x420 > [Wed May 25 05:27:59 2022] ? __tcp_transmit_skb+0x405/0x600 > [Wed May 25 05:27:59 2022] ? tcp_delack_timer_handler+0xb7/0x1b0 > [Wed May 25 05:27:59 2022] ? tcp_delack_timer+0x8b/0xa0 > [Wed May 25 05:27:59 2022] ? tcp_delack_timer_handler+0x1b0/0x1b0 > [Wed May 25 05:27:59 2022] ? call_timer_fn+0x2b/0x120 > [Wed May 25 05:27:59 2022] ? run_timer_softirq+0x1a6/0x420 > [Wed May 25 05:27:59 2022] ? update_load_avg+0x7e/0x640 > [Wed May 25 05:27:59 2022] ? update_curr+0xe1/0x1d0 > [Wed May 25 05:27:59 2022] ? __switch_to+0x7a/0x3e0 > [Wed May 25 05:27:59 2022] ? __do_softirq+0xda/0x2da > [Wed May 25 05:27:59 2022] ? sort_range+0x20/0x20 > [Wed May 25 05:27:59 2022] ? run_ksoftirqd+0x26/0x40 > [Wed May 25 05:27:59 2022] ? smpboot_thread_fn+0xb8/0x150 > [Wed May 25 05:27:59 2022] ? kthread+0x110/0x130 > [Wed May 25 05:27:59 2022] ? kthread_park+0x80/0x80 > [Wed May 25 05:27:59 2022] ? ret_from_fork+0x1f/0x30 > > I did some more tests. > > The test is single threaded. > Granule is 4k, limit is 2^20. > > When the 1/4 address space is occupied by iova, > Repeat the following two steps: > > 1. Randomly releases an iova. > 2. Allocate an iova of size 1 within the allocation limit of 2^20. > > Before improvement: >> Tracing 1 functions for "alloc_iova"... Hit Ctrl-C to end. >> ^C >> nsecs : count distribution >> 0 -> 1 : 0 | | >> 2 -> 3 : 0 | | >> 4 -> 7 : 0 | | >> 8 -> 15 : 0 | | >> 16 -> 31 : 0 | | >> 32 -> 63 : 0 | | >> 64 -> 127 : 0 | | >> 128 -> 255 : 0 | | >> 256 -> 511 : 352 >> | | >> 512 -> 1023 : 258078 >> |****************************************| >> 1024 -> 2047 : 3612 >> | | >> 2048 -> 4095 : 426 >> | | >> 4096 -> 8191 : 183 >> | | >> 8192 -> 16383 : 6 | | >> 16384 -> 32767 : 5 | | >> 32768 -> 65535 : 9 | | >> 65536 -> 131071 : 18 | | >> 131072 -> 262143 : 28 | | >> 262144 -> 524287 : 74 | | >> 524288 -> 1048575 : 109 >> | | >> 1048576 -> 2097151 : 170 >> | | >> 2097152 -> 4194303 : 100 >> | | >> 4194304 -> 8388607 : 1 | | >> >> avg = 3110 nsecs, total: 818614399 nsecs, count: 263171 >> >> Tracing 1 functions for "remove_iova"... Hit Ctrl-C to end. >> ^C >> nsecs : count distribution >> 0 -> 1 : 0 | | >> 2 -> 3 : 0 | | >> 4 -> 7 : 0 | | >> 8 -> 15 : 0 | | >> 16 -> 31 : 0 | | >> 32 -> 63 : 0 | | >> 64 -> 127 : 0 | | >> 128 -> 255 : 0 | | >> 256 -> 511 : 250651 >> |****************************************| >> 512 -> 1023 : 12405 >> |* | >> 1024 -> 2047 : 111 >> | | >> 2048 -> 4095 : 1 | | >> >> avg = 433 nsecs, total: 114136319 nsecs, count: 263168 > > With improvement: >> Tracing 1 functions for "alloc_iova"... Hit Ctrl-C to end. >> ^C >> nsecs : count distribution >> 0 -> 1 : 0 | | >> 2 -> 3 : 0 | | >> 4 -> 7 : 0 | | >> 8 -> 15 : 0 | | >> 16 -> 31 : 0 | | >> 32 -> 63 : 0 | | >> 64 -> 127 : 0 | | >> 128 -> 255 : 0 | | >> 256 -> 511 : 0 | | >> 512 -> 1023 : 258975 >> |****************************************| >> 1024 -> 2047 : 3618 >> | | >> 2048 -> 4095 : 497 >> | | >> 4096 -> 8191 : 74 | | >> 8192 -> 16383 : 4 | | >> 16384 -> 32767 : 1 | | >> >> avg = 637 nsecs, total: 167854061 nsecs, count: 263169 >> >> Tracing 1 functions for "remove_iova"... Hit Ctrl-C to end. >> ^C >> nsecs : count distribution >> 0 -> 1 : 0 | | >> 2 -> 3 : 0 | | >> 4 -> 7 : 0 | | >> 8 -> 15 : 0 | | >> 16 -> 31 : 0 | | >> 32 -> 63 : 0 | | >> 64 -> 127 : 0 | | >> 128 -> 255 : 0 | | >> 256 -> 511 : 221560 >> |****************************************| >> 512 -> 1023 : 41427 >> |******* | >> 1024 -> 2047 : 179 >> | | >> 2048 -> 4095 : 2 | | >> >> avg = 477 nsecs, total: 125540399 nsecs, count: 263168
Though only 3-4 drivers use alloc_iova() directly, in my understanding
your test has simulated the worst case, rcache doesn't work at all,
"alloc_iova" +“remove_iova” number looks great for worst case.
Reviewed-by: Ethan Zhao <haifeng.zhao@linux.intel.com>
> >> s/distbution/distribution ? > Sorry, it's a typo. > > I don't have a test program for "alloc_iova_fast + free_iova_fast" > right now. > > Thanks, > > Peng
-- "firm, enduring, strong, and long-lived"
| |