| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20220823214606.344269352@goodmis.org>
Date: Tue, 23 Aug 2022 17:46:06 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Tom Zanussi <zanussi@...nel.org>
Subject: [PATCH 0/4] tracing: Have filters and histograms use a call table instead of pointers
While looking at the histogram and filter code, I realized that it's filled
with function pointers. With retpolines causing a big slowdown, I thought
that was problematic. Thus, I decided to see what would happen if I changed
the function pointers into enums, and instead called a single function
that did a switch on those enums and called the necessary functions
directly. The results were pretty clear.
The first patch was to update the trace event benchmark event to include
a integer value "delta" of the delta that it took to complete
(it currently only shows the delta as part of a string). By doing
so, I could benchmark the histogram and filter logic with it.
Before this series, the histogram with a single filter (to ignore the
first event, which has a delta of zero), had:
# event histogram
#
# trigger info: hist:keys=delta:vals=hitcount:sort=delta:size=2048 if delta > 0 [active]
#
{ delta: 129 } hitcount: 2213
{ delta: 130 } hitcount: 285965
{ delta: 131 } hitcount: 1146545
{ delta: 132 } hitcount: 5185432
{ delta: 133 } hitcount: 19896215
{ delta: 134 } hitcount: 53118616
{ delta: 135 } hitcount: 83816709
{ delta: 136 } hitcount: 68329562
{ delta: 137 } hitcount: 41859349
{ delta: 138 } hitcount: 46257797
{ delta: 139 } hitcount: 54400831
{ delta: 140 } hitcount: 72875007
{ delta: 141 } hitcount: 76193272
{ delta: 142 } hitcount: 49504263
{ delta: 143 } hitcount: 38821072
{ delta: 144 } hitcount: 47702679
{ delta: 145 } hitcount: 41357297
{ delta: 146 } hitcount: 22058238
{ delta: 147 } hitcount: 9720002
{ delta: 148 } hitcount: 3193542
{ delta: 149 } hitcount: 927030
{ delta: 150 } hitcount: 850772
{ delta: 151 } hitcount: 1477380
{ delta: 152 } hitcount: 2687977
{ delta: 153 } hitcount: 2865985
{ delta: 154 } hitcount: 1977492
{ delta: 155 } hitcount: 2475607
{ delta: 156 } hitcount: 3403612
{ delta: 157 } hitcount: 2264011
{ delta: 158 } hitcount: 1096214
{ delta: 159 } hitcount: 504653
{ delta: 160 } hitcount: 218869
{ delta: 161 } hitcount: 103246
[..]
Where the bulk was around 142ns, and the fastest time was 129ns.
After this series:
# event histogram
#
# trigger info: hist:keys=delta:vals=hitcount:sort=delta:size=2048 if delta > 0 [active]
#
{ delta: 103 } hitcount: 60
{ delta: 104 } hitcount: 16966
{ delta: 105 } hitcount: 396625
{ delta: 106 } hitcount: 3223400
{ delta: 107 } hitcount: 12053754
{ delta: 108 } hitcount: 20241711
{ delta: 109 } hitcount: 14850200
{ delta: 110 } hitcount: 4946599
{ delta: 111 } hitcount: 3479315
{ delta: 112 } hitcount: 18698299
{ delta: 113 } hitcount: 62388733
{ delta: 114 } hitcount: 95803834
{ delta: 115 } hitcount: 58278130
{ delta: 116 } hitcount: 15364800
{ delta: 117 } hitcount: 5586866
{ delta: 118 } hitcount: 2346880
{ delta: 119 } hitcount: 1131091
{ delta: 120 } hitcount: 620896
{ delta: 121 } hitcount: 236652
{ delta: 122 } hitcount: 105957
{ delta: 123 } hitcount: 119107
{ delta: 124 } hitcount: 54494
{ delta: 125 } hitcount: 63856
{ delta: 126 } hitcount: 64454
{ delta: 127 } hitcount: 34818
{ delta: 128 } hitcount: 41446
{ delta: 129 } hitcount: 51242
{ delta: 130 } hitcount: 28361
{ delta: 131 } hitcount: 23926
{ delta: 132 } hitcount: 22253
{ delta: 133 } hitcount: 16994
{ delta: 134 } hitcount: 14970
{ delta: 135 } hitcount: 13464
{ delta: 136 } hitcount: 11452
{ delta: 137 } hitcount: 12212
{ delta: 138 } hitcount: 12280
{ delta: 139 } hitcount: 9127
{ delta: 140 } hitcount: 9553
Where the bulk was around 114ns and the fast time was 103ns.
That's almost a 20% speedup!!!
Steven Rostedt (Google) (4):
tracing: Add numeric delta time to the trace event benchmark
tracing/hist: Call hist functions directly via a switch statement
tracing: Move struct filter_pred into trace_events_filter.c
tracing/filter: Call filter predicate functions directly via a switch statement
----
kernel/trace/trace.h | 13 --
kernel/trace/trace_benchmark.c | 2 +-
kernel/trace/trace_benchmark.h | 8 +-
kernel/trace/trace_events_filter.c | 239 +++++++++++++++++++++++++-----------
kernel/trace/trace_events_hist.c | 244 +++++++++++++++++++++++++------------
5 files changed, 342 insertions(+), 164 deletions(-)
Powered by blists - more mailing lists