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linux: Make fewer (but still a lot of) regions in MemoryMap’s test

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The lots-of-regions tests in the MemoryMap test case were very
time-consuming, particularly in debug mode. MemoryMap.MapRunningChild
took as long as 15 seconds on-device (Nexus 5X), and the best result was
in the neighborhood of 7 seconds.

The bulk of the time spent in these tests was in ExpectMappings(), which
calls MemoryMap::FindMapping() in a loop to verify each region. Each
call to FindMapping() traverses the MemoryMap (internally, currently
just a std::vector<>) from the beginning. With the need to verify 4,096
regions, a single call to ExpectMappings() had to perform over 8,000,000
checks to find the regions it needed. In turn, ExpectMappings() is
called once by the SelfLargeMapFile test, and eight times by
MapRunningChild. By reducing the number of regions to 1,024, each call
to ExpectMappings() needs to perform “only” fewer than 600,000 checks.

After this change, MemoryMap.MapRunningChild completes in about a half a
second on-device.

https://crashpad.chromium.org/bug/181 is concerned with implementing a
RangeMap to serve MemoryMap and other similar code. After that’s done,
it, it should be feasible to raise the number of regions used for these
tests again.

Bug: crashpad:30, crashpad:181
Test: crashpad_util_test MemoryMap.SelfLargeMapFile:MemoryMap.MapRunningChild
Change-Id: I8ff88dac72a63c97ac937304b578fbe3b4ebf316
Reviewed-on: https://chromium-review.googlesource.com/494128
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
This commit is contained in:
Mark Mentovai 2017-05-02 16:50:14 -04:00
parent abbeffead9
commit dc60e106f3
1 changed files with 3 additions and 3 deletions
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6
util/linux/memory_map_test.cc
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@ -252,7 +252,7 @@ void ExpectMappings(const MemoryMap& map,
}
TEST(MemoryMap, SelfLargeMapFile) {
constexpr size_t kNumMappings = 4096;
constexpr size_t kNumMappings = 1024;
const size_t page_size = getpagesize();
ScopedMmap mappings;
@ -308,7 +308,7 @@ class MapRunningChildTest : public Multiprocess {
CheckedWriteFile(WritePipeHandle(), &region_addr, sizeof(region_addr));
// But don't stop there!
constexpr size_t kNumExtraMappings = 1024;
constexpr size_t kNumExtraMappings = 256;
ScopedMmap extra_mappings;
while (true) {
@ -325,7 +325,7 @@ class MapRunningChildTest : public Multiprocess {
}
}
static constexpr size_t kNumMappings = 4096;
static constexpr size_t kNumMappings = 1024;
const size_t page_size_;
DISALLOW_COPY_AND_ASSIGN(MapRunningChildTest);