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gprofng docs: provide help for <rate> == <interval>

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The help message from 'gprofng collect app -h', in
the section on <rate> == <interval>, had a dangling
reference to a non-existent manpage. Provide basic
info, including reasons for caution.
This commit is contained in:
Vladimir Mezentsev 2022-06-14 14:16:24 -07:00
parent 08328cfbaf
commit a675e77e55
1 changed files with 18 additions and 2 deletions
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20
gprofng/common/hwctable.c
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@ -5091,8 +5091,24 @@ hwc_usage_internal (int forKernel, FILE *f_usage, const char *cmd, const char *d
fprintf (f_usage, GTXT (" `lo' per-thread maximum rate of ~10 samples/second\n"));
fprintf (f_usage, GTXT (" `on' per-thread maximum rate of ~100 samples/second\n"));
fprintf (f_usage, GTXT (" `hi' per-thread maximum rate of ~1000 samples/second\n\n"));
fprintf (f_usage, GTXT (" <rate> == <interval>\n"));
fprintf (f_usage, GTXT (" event interval; see collect (1) for details\n\n"));
fprintf (f_usage, GTXT (" <rate> == <interval>\n"
" Fixed event interval value to trigger a sample.\n"
" Smaller intervals imply more frequent samples.\n"
" Example: when counting cycles on a 2 GHz processor,\n"
" an interval of 2,000,003 implies ~1000 samples/sec\n"
"\n"
" Use this feature with caution, because:\n"
" (1) Frequent sampling increases overhead and may disturb \n"
" other applications on your system.\n"
" (2) Event counts vary dramatically depending on the event \n"
" and depending on the application.\n"
" (3) A fixed event interval disables any other gprofng\n"
" internal mechanisms that may limit event rates.\n"
"\n"
" Guidelines: Aim at <1000 events per second. Start by \n"
" collecting with the 'hi' option; in the experiment overview,\n"
" notice how many events are recorded per second; divide by\n"
" 1000, and use that as your starting point.\n\n"));
fprintf (f_usage, GTXT (" A comma ',' followed immediately by white space may be omitted.\n\n"));
}