Messages in this thread | | | Date | Wed, 4 Nov 2015 10:54:33 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCHSET 0/4] perf report: Support folded callchain output (v4) |
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Hi Brendan,
On Tue, Nov 03, 2015 at 01:33:43PM -0800, Brendan Gregg wrote: > On Tue, Nov 3, 2015 at 6:40 AM, Arnaldo Carvalho de Melo > <arnaldo.melo@gmail.com> wrote: > > Em Tue, Nov 03, 2015 at 09:52:07PM +0900, Namhyung Kim escreveu: > >> Hello, > >> > >> This is what Brendan requested on the perf-users mailing list [1] to > >> support FlameGraphs [2] more efficiently. This patchset adds a few > >> more callchain options to adjust the output for it. > >> > >> * changes in v4) > >> - add missing doc update > >> - cleanup/fix callchain value print code > >> - add Acked-by from Brendan and Jiri > > > > Do those Acked-by stand? Things changed, the values moved from the end > > of the line to the start, etc. > > > [...] > > I'd Ack this change as it's a useful addition. It doesn't quite > address the folded-only output, but it's a step in that direction. I > think having the value at the start of a line only makes sense for the > perf report output containing the hist summary lines, for consistency.
Right, thanks!
> > Here's how I'd shuffle the output of this patch (ignore word wrap > issues with this email): > > # ./perf report --stdio -g folded,count,caller -F pid | \ > awk '/^ / { n = $1 } > /^[0-9]/ { split(n,a,":"); print a[2] "-" a[1] ";" $2,$1 }' > swapper-0;cpu_bringup_and_idle;cpu_startup_entry;default_idle_call;arch_cpu_idle;default_idle;xen_hypercall_sched_op > 809 > swapper-0;xen_start_kernel;x86_64_start_reservations;start_kernel;rest_init;cpu_startup_entry;default_idle_call;arch_cpu_idle;default_idle;xen_hypercall_sched_op > 135 > dd-30551;__GI___libc_read;entry_SYSCALL_64_fastpath;sys_read;vfs_read;__vfs_read;urandom_read;extract_entropy_user;extract_buf;check_events;xen_hypercall_xen_version > 63 > dd-30551;__GI___libc_read;entry_SYSCALL_64_fastpath;sys_read;vfs_read;__vfs_read;urandom_read;extract_entropy_user;extract_buf > 54 > dd-30551;__GI___libc_read;entry_SYSCALL_64_fastpath;sys_read;vfs_read;__vfs_read;urandom_read;extract_entropy_user;extract_buf;memset_erms > 3 > dd-30551;xen_irq_enable_direct_end;check_events;xen_hypercall_xen_version 3 > > So the output is folded stacks, prefixed by comm-PID. Shuffling the > summarized output is a lot better than doing a "perf script" dump and > re-processing call chains. (Note that since I'm using -F, I didn't > need --no-children;
Nope. The '-F pid' doesn't affect --children. It doesn't show the children overhead column but we still have hist entries for (synthesized) children..
$ perf report --no-children | wc -l 998
$ perf report --no-children -F pid,dso,sym | wc -l 998
$ perf report --children | wc -l 3229
$ perf report --children -F pid,dso,sym | wc -l 3202
So I think you still need to use --no-children (or set report.children config variable to false) for your script.
> and with "-g count", I didn't need --show-nr-samples.)
Yes, I used -n/--show-nr-samples just to check the number is correct.
> > I notice the fields (-F) option already has this precedent: > > - "comm": prints PID:comm > - "pid": prints PID
It's opposite: "comm" prints comm, "pid" prints PID:comm. :)
> > If these were added to -g, along with a no-hists, then the two types > of folded-only output could be generated using: > > perf report --stdio -g folded,count,comm,no-hists,caller > perf report --stdio -g folded,count,pid,no-hists,caller
As I said, using fields like comm, pid requires to have same keys in --sort option. So it's basically unreliable to use those specific field names in the -g option IMHO. I suggested to use 'info' (yes, it needs better name) to print all sort keys.
> > ... although "no-hists" doesn't hit me as intuitive. How about "-F > none" to specify zero columns? ie: > > perf report --stdio -g folded,count,comm,caller -F none > perf report --stdio -g folded,count,pid,caller -F none
Ah, makes sense. So it'd look like
$ perf report --stdio -g folded,count,info -F none -s comm $ perf report --stdio -g folded,count,info -F none -s pid
The output would be
809 swapper-0 cpu_bringup_and_idle;cpu_startup_entry;default_idle_call;arch_cpu_idle;default_idle;xen_hypercall_sched_op
Thoughts?
Thanks, Namhyung
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