On Fri, Aug 9, 2024 at 11:34 AM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Fri, Aug 9, 2024 at 12:16 AM Liao, Chang <liaochang1@xxxxxxxxxx> wrote: > > > > > > > > 在 2024/8/9 2:26, Andrii Nakryiko 写道: > > > On Thu, Aug 8, 2024 at 1:45 AM Liao, Chang <liaochang1@xxxxxxxxxx> wrote: > > >> > > >> Hi Andrii and Oleg. > > >> > > >> This patch sent by me two weeks ago also aim to optimize the performance of uprobe > > >> on arm64. I notice recent discussions on the performance and scalability of uprobes > > >> within the mailing list. Considering this interest, I've added you and other relevant > > >> maintainers to the CC list for broader visibility and potential collaboration. > > >> > > > > > > Hi Liao, > > > > > > As you can see there is an active work to improve uprobes, that > > > changes lifetime management of uprobes, removes a bunch of locks taken > > > in the uprobe/uretprobe hot path, etc. It would be nice if you can > > > hold off a bit with your changes until all that lands. And then > > > re-benchmark, as costs might shift. > > > > Andrii, I'm trying to integrate your lockless changes into the upstream > > next-20240806 kernel tree. And I ran into some conflicts. please let me > > know which kernel you're currently working on. > > > > My patches are based on tip/perf/core. But I also just pushed all the > changes I have accumulated (including patches I haven't sent for > review just yet), plus your patches for sighand lock removed applied > on top into [0]. So you can take a look and use that as a base for > now. Keep in mind, a bunch of those patches might still change, but > this should give you the best currently achievable performance with > uprobes/uretprobes. E.g., I'm getting something like below on x86-64 > (note somewhat linear scalability with number of CPU cores, with > per-CPU performance *slowly* declining): > > uprobe-nop ( 1 cpus): 3.565 ± 0.004M/s ( 3.565M/s/cpu) > uprobe-nop ( 2 cpus): 6.742 ± 0.009M/s ( 3.371M/s/cpu) > uprobe-nop ( 3 cpus): 10.029 ± 0.056M/s ( 3.343M/s/cpu) > uprobe-nop ( 4 cpus): 13.118 ± 0.014M/s ( 3.279M/s/cpu) > uprobe-nop ( 5 cpus): 16.360 ± 0.011M/s ( 3.272M/s/cpu) > uprobe-nop ( 6 cpus): 19.650 ± 0.045M/s ( 3.275M/s/cpu) > uprobe-nop ( 7 cpus): 22.926 ± 0.010M/s ( 3.275M/s/cpu) > uprobe-nop ( 8 cpus): 24.707 ± 0.025M/s ( 3.088M/s/cpu) > uprobe-nop (10 cpus): 30.842 ± 0.018M/s ( 3.084M/s/cpu) > uprobe-nop (12 cpus): 33.623 ± 0.037M/s ( 2.802M/s/cpu) > uprobe-nop (14 cpus): 39.199 ± 0.009M/s ( 2.800M/s/cpu) > uprobe-nop (16 cpus): 41.698 ± 0.018M/s ( 2.606M/s/cpu) > uprobe-nop (24 cpus): 65.078 ± 0.018M/s ( 2.712M/s/cpu) > uprobe-nop (32 cpus): 84.580 ± 0.017M/s ( 2.643M/s/cpu) > uprobe-nop (40 cpus): 101.992 ± 0.268M/s ( 2.550M/s/cpu) > uprobe-nop (48 cpus): 101.032 ± 1.428M/s ( 2.105M/s/cpu) > uprobe-nop (56 cpus): 110.986 ± 0.736M/s ( 1.982M/s/cpu) > uprobe-nop (64 cpus): 124.145 ± 0.110M/s ( 1.940M/s/cpu) > uprobe-nop (72 cpus): 134.940 ± 0.200M/s ( 1.874M/s/cpu) > uprobe-nop (80 cpus): 143.918 ± 0.235M/s ( 1.799M/s/cpu) > > uretprobe-nop ( 1 cpus): 1.987 ± 0.001M/s ( 1.987M/s/cpu) > uretprobe-nop ( 2 cpus): 3.766 ± 0.003M/s ( 1.883M/s/cpu) > uretprobe-nop ( 3 cpus): 5.638 ± 0.002M/s ( 1.879M/s/cpu) > uretprobe-nop ( 4 cpus): 7.275 ± 0.003M/s ( 1.819M/s/cpu) > uretprobe-nop ( 5 cpus): 9.124 ± 0.004M/s ( 1.825M/s/cpu) > uretprobe-nop ( 6 cpus): 10.818 ± 0.007M/s ( 1.803M/s/cpu) > uretprobe-nop ( 7 cpus): 12.721 ± 0.014M/s ( 1.817M/s/cpu) > uretprobe-nop ( 8 cpus): 13.639 ± 0.007M/s ( 1.705M/s/cpu) > uretprobe-nop (10 cpus): 17.023 ± 0.009M/s ( 1.702M/s/cpu) > uretprobe-nop (12 cpus): 18.576 ± 0.014M/s ( 1.548M/s/cpu) > uretprobe-nop (14 cpus): 21.660 ± 0.004M/s ( 1.547M/s/cpu) > uretprobe-nop (16 cpus): 22.922 ± 0.013M/s ( 1.433M/s/cpu) > uretprobe-nop (24 cpus): 34.756 ± 0.069M/s ( 1.448M/s/cpu) > uretprobe-nop (32 cpus): 44.869 ± 0.153M/s ( 1.402M/s/cpu) > uretprobe-nop (40 cpus): 53.397 ± 0.220M/s ( 1.335M/s/cpu) > uretprobe-nop (48 cpus): 48.903 ± 2.277M/s ( 1.019M/s/cpu) > uretprobe-nop (56 cpus): 42.144 ± 1.206M/s ( 0.753M/s/cpu) > uretprobe-nop (64 cpus): 42.656 ± 1.104M/s ( 0.666M/s/cpu) > uretprobe-nop (72 cpus): 46.299 ± 1.443M/s ( 0.643M/s/cpu) > uretprobe-nop (80 cpus): 46.469 ± 0.808M/s ( 0.581M/s/cpu) > > uprobe-ret ( 1 cpus): 1.219 ± 0.008M/s ( 1.219M/s/cpu) > uprobe-ret ( 2 cpus): 1.862 ± 0.008M/s ( 0.931M/s/cpu) > uprobe-ret ( 3 cpus): 2.874 ± 0.005M/s ( 0.958M/s/cpu) > uprobe-ret ( 4 cpus): 3.512 ± 0.002M/s ( 0.878M/s/cpu) > uprobe-ret ( 5 cpus): 3.549 ± 0.001M/s ( 0.710M/s/cpu) > uprobe-ret ( 6 cpus): 3.425 ± 0.003M/s ( 0.571M/s/cpu) > uprobe-ret ( 7 cpus): 3.551 ± 0.009M/s ( 0.507M/s/cpu) > uprobe-ret ( 8 cpus): 3.050 ± 0.002M/s ( 0.381M/s/cpu) > uprobe-ret (10 cpus): 2.706 ± 0.002M/s ( 0.271M/s/cpu) > uprobe-ret (12 cpus): 2.588 ± 0.003M/s ( 0.216M/s/cpu) > uprobe-ret (14 cpus): 2.589 ± 0.003M/s ( 0.185M/s/cpu) > uprobe-ret (16 cpus): 2.575 ± 0.001M/s ( 0.161M/s/cpu) > uprobe-ret (24 cpus): 1.808 ± 0.011M/s ( 0.075M/s/cpu) > uprobe-ret (32 cpus): 1.853 ± 0.001M/s ( 0.058M/s/cpu) > uprobe-ret (40 cpus): 1.952 ± 0.002M/s ( 0.049M/s/cpu) > uprobe-ret (48 cpus): 2.075 ± 0.007M/s ( 0.043M/s/cpu) > uprobe-ret (56 cpus): 2.441 ± 0.004M/s ( 0.044M/s/cpu) > uprobe-ret (64 cpus): 1.880 ± 0.012M/s ( 0.029M/s/cpu) > uprobe-ret (72 cpus): 0.962 ± 0.002M/s ( 0.013M/s/cpu) > uprobe-ret (80 cpus): 1.040 ± 0.011M/s ( 0.013M/s/cpu) > > uretprobe-ret ( 1 cpus): 0.981 ± 0.000M/s ( 0.981M/s/cpu) > uretprobe-ret ( 2 cpus): 1.421 ± 0.001M/s ( 0.711M/s/cpu) > uretprobe-ret ( 3 cpus): 2.050 ± 0.003M/s ( 0.683M/s/cpu) > uretprobe-ret ( 4 cpus): 2.596 ± 0.002M/s ( 0.649M/s/cpu) > uretprobe-ret ( 5 cpus): 3.105 ± 0.003M/s ( 0.621M/s/cpu) > uretprobe-ret ( 6 cpus): 3.886 ± 0.002M/s ( 0.648M/s/cpu) > uretprobe-ret ( 7 cpus): 3.016 ± 0.001M/s ( 0.431M/s/cpu) > uretprobe-ret ( 8 cpus): 2.903 ± 0.000M/s ( 0.363M/s/cpu) > uretprobe-ret (10 cpus): 2.755 ± 0.001M/s ( 0.276M/s/cpu) > uretprobe-ret (12 cpus): 2.400 ± 0.001M/s ( 0.200M/s/cpu) > uretprobe-ret (14 cpus): 3.972 ± 0.001M/s ( 0.284M/s/cpu) > uretprobe-ret (16 cpus): 3.940 ± 0.003M/s ( 0.246M/s/cpu) > uretprobe-ret (24 cpus): 3.002 ± 0.003M/s ( 0.125M/s/cpu) > uretprobe-ret (32 cpus): 3.018 ± 0.003M/s ( 0.094M/s/cpu) > uretprobe-ret (40 cpus): 1.846 ± 0.000M/s ( 0.046M/s/cpu) > uretprobe-ret (48 cpus): 2.487 ± 0.004M/s ( 0.052M/s/cpu) > uretprobe-ret (56 cpus): 2.470 ± 0.006M/s ( 0.044M/s/cpu) > uretprobe-ret (64 cpus): 2.027 ± 0.014M/s ( 0.032M/s/cpu) > uretprobe-ret (72 cpus): 1.108 ± 0.011M/s ( 0.015M/s/cpu) > uretprobe-ret (80 cpus): 0.982 ± 0.005M/s ( 0.012M/s/cpu) > > > -ret variants (single-stepping case for x86-64) still suck, but they > suck 2x less now with your patches :) Clearly more work ahead for > those, though. > Quick profiling shows that it's mostly xol_take_insn_slot() and xol_free_insn_slot(), now. So it seems like your planned work might help here. > > [0] https://github.com/anakryiko/linux/commits/uprobes-lockless-cumulative/ > > > > Thanks. > > > > > > > > But also see some remarks below. > > > > > >> Thanks. > > >> > > >> 在 2024/7/27 17:44, Liao Chang 写道: > > >>> The profiling result of single-thread model of selftests bench reveals > > >>> performance bottlenecks in find_uprobe() and caches_clean_inval_pou() on > > >>> ARM64. On my local testing machine, 5% of CPU time is consumed by > > >>> find_uprobe() for trig-uprobe-ret, while caches_clean_inval_pou() take > > >>> about 34% of CPU time for trig-uprobe-nop and trig-uprobe-push. > > >>> > > >>> This patch introduce struct uprobe_breakpoint to track previously > > >>> allocated insn_slot for frequently hit uprobe. it effectively reduce the > > >>> need for redundant insn_slot writes and subsequent expensive cache > > >>> flush, especially on architecture like ARM64. This patch has been tested > > >>> on Kunpeng916 (Hi1616), 4 NUMA nodes, 64 cores@ 2.4GHz. The selftest > > >>> bench and Redis GET/SET benchmark result below reveal obivious > > >>> performance gain. > > >>> > > >>> before-opt > > >>> ---------- > > >>> trig-uprobe-nop: 0.371 ± 0.001M/s (0.371M/prod) > > >>> trig-uprobe-push: 0.370 ± 0.001M/s (0.370M/prod) > > >>> trig-uprobe-ret: 1.637 ± 0.001M/s (1.647M/prod) > > > > > > I'm surprised that nop and push variants are much slower than ret > > > variant. This is exactly opposite on x86-64. Do you have an > > > explanation why this might be happening? I see you are trying to > > > optimize xol_get_insn_slot(), but that is (at least for x86) a slow > > > variant of uprobe that normally shouldn't be used. Typically uprobe is > > > installed on nop (for USDT) and on function entry (which would be push > > > variant, `push %rbp` instruction). > > > > > > ret variant, for x86-64, causes one extra step to go back to user > > > space to execute original instruction out-of-line, and then trapping > > > back to kernel for running uprobe. Which is what you normally want to > > > avoid. > > > > > > What I'm getting at here. It seems like maybe arm arch is missing fast > > > emulated implementations for nops/push or whatever equivalents for > > > ARM64 that is. Please take a look at that and see why those are slow > > > and whether you can make those into fast uprobe cases? > > > > I will spend the weekend figuring out the questions you raised. Thanks for > > pointing them out. > > > > > > > >>> trig-uretprobe-nop: 0.331 ± 0.004M/s (0.331M/prod) > > >>> trig-uretprobe-push: 0.333 ± 0.000M/s (0.333M/prod) > > >>> trig-uretprobe-ret: 0.854 ± 0.002M/s (0.854M/prod) > > >>> Redis SET (RPS) uprobe: 42728.52 > > >>> Redis GET (RPS) uprobe: 43640.18 > > >>> Redis SET (RPS) uretprobe: 40624.54 > > >>> Redis GET (RPS) uretprobe: 41180.56 > > >>> > > >>> after-opt > > >>> --------- > > >>> trig-uprobe-nop: 0.916 ± 0.001M/s (0.916M/prod) > > >>> trig-uprobe-push: 0.908 ± 0.001M/s (0.908M/prod) > > >>> trig-uprobe-ret: 1.855 ± 0.000M/s (1.855M/prod) > > >>> trig-uretprobe-nop: 0.640 ± 0.000M/s (0.640M/prod) > > >>> trig-uretprobe-push: 0.633 ± 0.001M/s (0.633M/prod) > > >>> trig-uretprobe-ret: 0.978 ± 0.003M/s (0.978M/prod) > > >>> Redis SET (RPS) uprobe: 43939.69 > > >>> Redis GET (RPS) uprobe: 45200.80 > > >>> Redis SET (RPS) uretprobe: 41658.58 > > >>> Redis GET (RPS) uretprobe: 42805.80 > > >>> > > >>> While some uprobes might still need to share the same insn_slot, this > > >>> patch compare the instructions in the resued insn_slot with the > > >>> instructions execute out-of-line firstly to decides allocate a new one > > >>> or not. > > >>> > > >>> Additionally, this patch use a rbtree associated with each thread that > > >>> hit uprobes to manage these allocated uprobe_breakpoint data. Due to the > > >>> rbtree of uprobe_breakpoints has smaller node, better locality and less > > >>> contention, it result in faster lookup times compared to find_uprobe(). > > >>> > > >>> The other part of this patch are some necessary memory management for > > >>> uprobe_breakpoint data. A uprobe_breakpoint is allocated for each newly > > >>> hit uprobe that doesn't already have a corresponding node in rbtree. All > > >>> uprobe_breakpoints will be freed when thread exit. > > >>> > > >>> Signed-off-by: Liao Chang <liaochang1@xxxxxxxxxx> > > >>> --- > > >>> include/linux/uprobes.h | 3 + > > >>> kernel/events/uprobes.c | 246 +++++++++++++++++++++++++++++++++------- > > >>> 2 files changed, 211 insertions(+), 38 deletions(-) > > >>> > > > > > > [...] > > > > -- > > BR > > Liao, Chang
