On Sat, Jan 16, 2021 at 1:13 AM Nick Desaulniers <nick.desaulniers@xxxxxxxxx> wrote: > > > On Wed, Jan 13, 2021 at 8:07 PM Nick Desaulniers > > <ndesaulniers@xxxxxxxxxx> wrote: > > > > > > On Wed, Jan 13, 2021 at 12:55 PM Nathan Chancellor > > > <natechancellor@xxxxxxxxx> wrote: > > > > > > > > However, I see an issue with actually using the data: > > > > > > > > $ sudo -s > > > > # mount -t debugfs none /sys/kernel/debug > > > > # cp -a /sys/kernel/debug/pgo/profraw vmlinux.profraw > > > > # chown nathan:nathan vmlinux.profraw > > > > # exit > > > > $ tc-build/build/llvm/stage1/bin/llvm-profdata merge --output=vmlinux.profdata vmlinux.profraw > > > > warning: vmlinux.profraw: Invalid instrumentation profile data (bad magic) > > > > error: No profiles could be merged. > > > > > > > > Am I holding it wrong? :) Note, this is virtualized, I do not have any > > > > "real" x86 hardware that I can afford to test on right now. > > > > > > Same. > > > > > > I think the magic calculation in this patch may differ from upstream > > > llvm: https://github.com/llvm/llvm-project/blob/49142991a685bd427d7e877c29c77371dfb7634c/llvm/include/llvm/ProfileData/SampleProf.h#L96-L101 > > > > Err...it looks like it was the padding calculation. With that fixed > > up, we can query the profile data to get insights on the most heavily > > called functions. Here's what my top 20 are (reset, then watch 10 > > minutes worth of cat videos on youtube while running `find /` and > > sleeping at my desk). Anything curious stand out to anyone? > > Hello world from my personal laptop whose kernel was rebuilt with > profiling data! Wow, I can run `find /` and watch cat videos on youtube > so fast! Users will love this! /s > > Checking the sections sizes of .text.hot. and .text.unlikely. looks > good! > On each rebuild I need to pass to make ...? LLVM=1 -fprofile-use=vmlinux.profdata Did you try together with passing LLVM_IAS=1 to make? - Sedat - > > > > $ llvm-profdata show -topn=20 /tmp/vmlinux.profraw > > Instrumentation level: IR entry_first = 0 > > Total functions: 48970 > > Maximum function count: 62070879 > > Maximum internal block count: 83221158 > > Top 20 functions with the largest internal block counts: > > drivers/tty/n_tty.c:n_tty_write, max count = 83221158 > > rcu_read_unlock_strict, max count = 62070879 > > _cond_resched, max count = 25486882 > > rcu_all_qs, max count = 25451477 > > drivers/cpuidle/poll_state.c:poll_idle, max count = 23618576 > > _raw_spin_unlock_irqrestore, max count = 18874121 > > drivers/cpuidle/governors/menu.c:menu_select, max count = 18721624 > > _raw_spin_lock_irqsave, max count = 18509161 > > memchr, max count = 15525452 > > _raw_spin_lock, max count = 15484254 > > __mod_memcg_state, max count = 14604619 > > __mod_memcg_lruvec_state, max count = 14602783 > > fs/ext4/hash.c:str2hashbuf_signed, max count = 14098424 > > __mod_lruvec_state, max count = 12527154 > > __mod_node_page_state, max count = 12525172 > > native_sched_clock, max count = 8904692 > > sched_clock_cpu, max count = 8895832 > > sched_clock, max count = 8894627 > > kernel/entry/common.c:exit_to_user_mode_prepare, max count = 8289031 > > fpregs_assert_state_consistent, max count = 8287198 > > > > -- > > Thanks, > > ~Nick Desaulniers > > > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210116001324.2865-1-nick.desaulniers%40gmail.com.
