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set test "optim_stats"
# This is a test for stat run time optimizations. Each stat has a list of
# requested statistical operators. For instance, if a script uses stat x,
# and only refers to @avg(x), then the list of requested statistical operators
# for given stat x is @count, @sum, and @avg. The @min(x) and @max(x) are
# not in the list, and thus do not need to be avaluated at the _stp_stat_add()
# time (iow, at the x<<<val time). Optimization based on this makes the
# systemtap runtime run faster. The goal of this test is to verify that this
# sort of optimizations actually works in a measurable way.
#
# At the moment, the available stat operators are @count, @sum, @min, @max,
# @avg, and @variance. The most computionally expensive is @variance.
# Detecting the variance optimization is quite simple. Other operators are
# computionally cheap and thus detecting their respective optimizations is
# somewhat tricky on a multiuser/multitasking system, where so many irrelevant
# bearings are affecting our fragile measurement. In this case we must set
# the treshold distinguishing between the PASS and FAIL pretty carefully. Just
# slightly above the "noise". This testcase is sentenced to be fragile by it's
# nature though.
#
# One of the basic assumptions for this sort of test is that if we compare stats
# having identical list of requested statistical operators, we should get very
# similar results. It turns out, that to achieve this, we can't simply feed the
# values into measured stats in straightforward order. Instead, we need to baffle
# the optimizations under the hood by complicating the "feed" order slightly.
# After verifying this assumption, we can start comparing different stats.
#
# Since verifying the @variance optimization is much easirer and doesn't require
# so many time consuming iterations to get reasonable results, this test is
# divided into two parts, TEST 1, and TEST 2, where in TEST 1 we focus on the
# optimization for @count, @sum, @min, and @max, and then, in TEST 2, we test the
# @variance optimization separately. This makes the test itself run faster.
#
# Define the tresholds
switch -regexp $::tcl_platform(machine) {
{^(aarch64|ppc64le|ppc64|s390x)$} {
array set treshold [list {TEST1} {0} \
{TEST2} {10} \
{TEST3} {0} \
{TEST4} {10} ]
}
default {
array set treshold [list {TEST1} {5} \
{TEST2} {20} \
{TEST3} {5} \
{TEST4} {20} ]
}
}
if {![installtest_p]} {
untested $test
return
}
for {set i 1} {$i <= 2} {incr i} {
foreach runtime [get_runtime_list] {
if {$runtime != ""} {
spawn stap -u --runtime=$runtime -g --suppress-time-limits $srcdir/$subdir/$test$i.stp
} else {
spawn stap -u -g --suppress-time-limits $srcdir/$subdir/$test$i.stp
}
expect {
-timeout 300
-re {^IGNORE[^\r\n]+\r\n} { exp_continue }
-re {^TEST[0-9]\ [^\r\n]+\r\n} {
set key [lindex [split $expect_out(0,string)] 0]
set val [lindex [split $expect_out(0,string)] 1]
set lim $treshold($key)
if {$val >= $lim} {
pass "$key $runtime ($lim, $val)"
} else {
fail "$key $runtime ($lim, $val)"
}
exp_continue
}
timeout {fail "$test: unexpected timeout"}
eof { }
}
catch {close}; catch {wait}
}
}
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