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fsmonitor: add a performance test

Add a test utility (test-drop-caches) that flushes all changes to disk
then drops file system cache on Windows, Linux, and OSX.

Add a perf test (p7519-fsmonitor.sh) for fsmonitor.

By default, the performance test will utilize the Watchman file system
monitor if it is installed.  If Watchman is not installed, it will use a
dummy integration script that does not report any new or modified files.
The dummy script has very little overhead which provides optimistic results.

The performance test will also use the untracked cache feature if it is
available as fsmonitor uses it to speed up scanning for untracked files.

There are 4 environment variables that can be used to alter the default
behavior of the performance test:

GIT_PERF_7519_UNTRACKED_CACHE: used to configure core.untrackedCache
GIT_PERF_7519_SPLIT_INDEX: used to configure core.splitIndex
GIT_PERF_7519_FSMONITOR: used to configure core.fsmonitor
GIT_PERF_7519_DROP_CACHE: if set, the OS caches are dropped between tests

The big win for using fsmonitor is the elimination of the need to scan the
working directory looking for changed and untracked files. If the file
information is all cached in RAM, the benefits are reduced.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ben Peart 2017-09-22 12:35:48 -04:00 committed by Junio C Hamano
parent def4376711
commit 14527b3002
4 changed files with 350 additions and 0 deletions

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@ -638,6 +638,7 @@ TEST_PROGRAMS_NEED_X += test-ctype
TEST_PROGRAMS_NEED_X += test-config
TEST_PROGRAMS_NEED_X += test-date
TEST_PROGRAMS_NEED_X += test-delta
TEST_PROGRAMS_NEED_X += test-drop-caches
TEST_PROGRAMS_NEED_X += test-dump-cache-tree
TEST_PROGRAMS_NEED_X += test-dump-fsmonitor
TEST_PROGRAMS_NEED_X += test-dump-split-index

1
t/helper/.gitignore vendored
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@ -3,6 +3,7 @@
/test-config
/test-date
/test-delta
/test-drop-caches
/test-dump-cache-tree
/test-dump-fsmonitor
/test-dump-split-index

164
t/helper/test-drop-caches.c Normal file
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@ -0,0 +1,164 @@
#include "git-compat-util.h"
#if defined(GIT_WINDOWS_NATIVE)
static int cmd_sync(void)
{
char Buffer[MAX_PATH];
DWORD dwRet;
char szVolumeAccessPath[] = "\\\\.\\X:";
HANDLE hVolWrite;
int success = 0;
dwRet = GetCurrentDirectory(MAX_PATH, Buffer);
if ((0 == dwRet) || (dwRet > MAX_PATH))
return error("Error getting current directory");
if ((Buffer[0] < 'A') || (Buffer[0] > 'Z'))
return error("Invalid drive letter '%c'", Buffer[0]);
szVolumeAccessPath[4] = Buffer[0];
hVolWrite = CreateFile(szVolumeAccessPath, GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
if (INVALID_HANDLE_VALUE == hVolWrite)
return error("Unable to open volume for writing, need admin access");
success = FlushFileBuffers(hVolWrite);
if (!success)
error("Unable to flush volume");
CloseHandle(hVolWrite);
return !success;
}
#define STATUS_SUCCESS (0x00000000L)
#define STATUS_PRIVILEGE_NOT_HELD (0xC0000061L)
typedef enum _SYSTEM_INFORMATION_CLASS {
SystemMemoryListInformation = 80,
} SYSTEM_INFORMATION_CLASS;
typedef enum _SYSTEM_MEMORY_LIST_COMMAND {
MemoryCaptureAccessedBits,
MemoryCaptureAndResetAccessedBits,
MemoryEmptyWorkingSets,
MemoryFlushModifiedList,
MemoryPurgeStandbyList,
MemoryPurgeLowPriorityStandbyList,
MemoryCommandMax
} SYSTEM_MEMORY_LIST_COMMAND;
static BOOL GetPrivilege(HANDLE TokenHandle, LPCSTR lpName, int flags)
{
BOOL bResult;
DWORD dwBufferLength;
LUID luid;
TOKEN_PRIVILEGES tpPreviousState;
TOKEN_PRIVILEGES tpNewState;
dwBufferLength = 16;
bResult = LookupPrivilegeValueA(0, lpName, &luid);
if (bResult) {
tpNewState.PrivilegeCount = 1;
tpNewState.Privileges[0].Luid = luid;
tpNewState.Privileges[0].Attributes = 0;
bResult = AdjustTokenPrivileges(TokenHandle, 0, &tpNewState,
(DWORD)((LPBYTE)&(tpNewState.Privileges[1]) - (LPBYTE)&tpNewState),
&tpPreviousState, &dwBufferLength);
if (bResult) {
tpPreviousState.PrivilegeCount = 1;
tpPreviousState.Privileges[0].Luid = luid;
tpPreviousState.Privileges[0].Attributes = flags != 0 ? 2 : 0;
bResult = AdjustTokenPrivileges(TokenHandle, 0, &tpPreviousState,
dwBufferLength, 0, 0);
}
}
return bResult;
}
static int cmd_dropcaches(void)
{
HANDLE hProcess = GetCurrentProcess();
HANDLE hToken;
HMODULE ntdll;
DWORD(WINAPI *NtSetSystemInformation)(INT, PVOID, ULONG);
SYSTEM_MEMORY_LIST_COMMAND command;
int status;
if (!OpenProcessToken(hProcess, TOKEN_QUERY | TOKEN_ADJUST_PRIVILEGES, &hToken))
return error("Can't open current process token");
if (!GetPrivilege(hToken, "SeProfileSingleProcessPrivilege", 1))
return error("Can't get SeProfileSingleProcessPrivilege");
CloseHandle(hToken);
ntdll = LoadLibrary("ntdll.dll");
if (!ntdll)
return error("Can't load ntdll.dll, wrong Windows version?");
NtSetSystemInformation =
(DWORD(WINAPI *)(INT, PVOID, ULONG))GetProcAddress(ntdll, "NtSetSystemInformation");
if (!NtSetSystemInformation)
return error("Can't get function addresses, wrong Windows version?");
command = MemoryPurgeStandbyList;
status = NtSetSystemInformation(
SystemMemoryListInformation,
&command,
sizeof(SYSTEM_MEMORY_LIST_COMMAND)
);
if (status == STATUS_PRIVILEGE_NOT_HELD)
error("Insufficient privileges to purge the standby list, need admin access");
else if (status != STATUS_SUCCESS)
error("Unable to execute the memory list command %d", status);
FreeLibrary(ntdll);
return status;
}
#elif defined(__linux__)
static int cmd_sync(void)
{
return system("sync");
}
static int cmd_dropcaches(void)
{
return system("echo 3 | sudo tee /proc/sys/vm/drop_caches");
}
#elif defined(__APPLE__)
static int cmd_sync(void)
{
return system("sync");
}
static int cmd_dropcaches(void)
{
return system("sudo purge");
}
#else
static int cmd_sync(void)
{
return 0;
}
static int cmd_dropcaches(void)
{
return error("drop caches not implemented on this platform");
}
#endif
int cmd_main(int argc, const char **argv)
{
cmd_sync();
return cmd_dropcaches();
}

184
t/perf/p7519-fsmonitor.sh Executable file
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@ -0,0 +1,184 @@
#!/bin/sh
test_description="Test core.fsmonitor"
. ./perf-lib.sh
#
# Performance test for the fsmonitor feature which enables git to talk to a
# file system change monitor and avoid having to scan the working directory
# for new or modified files.
#
# By default, the performance test will utilize the Watchman file system
# monitor if it is installed. If Watchman is not installed, it will use a
# dummy integration script that does not report any new or modified files.
# The dummy script has very little overhead which provides optimistic results.
#
# The performance test will also use the untracked cache feature if it is
# available as fsmonitor uses it to speed up scanning for untracked files.
#
# There are 3 environment variables that can be used to alter the default
# behavior of the performance test:
#
# GIT_PERF_7519_UNTRACKED_CACHE: used to configure core.untrackedCache
# GIT_PERF_7519_SPLIT_INDEX: used to configure core.splitIndex
# GIT_PERF_7519_FSMONITOR: used to configure core.fsMonitor
#
# The big win for using fsmonitor is the elimination of the need to scan the
# working directory looking for changed and untracked files. If the file
# information is all cached in RAM, the benefits are reduced.
#
# GIT_PERF_7519_DROP_CACHE: if set, the OS caches are dropped between tests
#
test_perf_large_repo
test_checkout_worktree
test_lazy_prereq UNTRACKED_CACHE '
{ git update-index --test-untracked-cache; ret=$?; } &&
test $ret -ne 1
'
test_lazy_prereq WATCHMAN '
{ command -v watchman >/dev/null 2>&1; ret=$?; } &&
test $ret -ne 1
'
if test_have_prereq WATCHMAN
then
# Convert unix style paths to escaped Windows style paths for Watchman
case "$(uname -s)" in
MSYS_NT*)
GIT_WORK_TREE="$(cygpath -aw "$PWD" | sed 's,\\,/,g')"
;;
*)
GIT_WORK_TREE="$PWD"
;;
esac
fi
if test -n "$GIT_PERF_7519_DROP_CACHE"
then
# When using GIT_PERF_7519_DROP_CACHE, GIT_PERF_REPEAT_COUNT must be 1 to
# generate valid results. Otherwise the caching that happens for the nth
# run will negate the validity of the comparisons.
if test "$GIT_PERF_REPEAT_COUNT" -ne 1
then
echo "warning: Setting GIT_PERF_REPEAT_COUNT=1" >&2
GIT_PERF_REPEAT_COUNT=1
fi
fi
test_expect_success "setup for fsmonitor" '
# set untrackedCache depending on the environment
if test -n "$GIT_PERF_7519_UNTRACKED_CACHE"
then
git config core.untrackedCache "$GIT_PERF_7519_UNTRACKED_CACHE"
else
if test_have_prereq UNTRACKED_CACHE
then
git config core.untrackedCache true
else
git config core.untrackedCache false
fi
fi &&
# set core.splitindex depending on the environment
if test -n "$GIT_PERF_7519_SPLIT_INDEX"
then
git config core.splitIndex "$GIT_PERF_7519_SPLIT_INDEX"
fi &&
# set INTEGRATION_SCRIPT depending on the environment
if test -n "$GIT_PERF_7519_FSMONITOR"
then
INTEGRATION_SCRIPT="$GIT_PERF_7519_FSMONITOR"
else
#
# Choose integration script based on existence of Watchman.
# If Watchman exists, watch the work tree and attempt a query.
# If everything succeeds, use Watchman integration script,
# else fall back to an empty integration script.
#
mkdir .git/hooks &&
if test_have_prereq WATCHMAN
then
INTEGRATION_SCRIPT=".git/hooks/fsmonitor-watchman" &&
cp "$TEST_DIRECTORY/../templates/hooks--fsmonitor-watchman.sample" "$INTEGRATION_SCRIPT" &&
watchman watch "$GIT_WORK_TREE" &&
watchman watch-list | grep -q -F "$GIT_WORK_TREE"
else
INTEGRATION_SCRIPT=".git/hooks/fsmonitor-empty" &&
write_script "$INTEGRATION_SCRIPT"<<-\EOF
EOF
fi
fi &&
git config core.fsmonitor "$INTEGRATION_SCRIPT" &&
git update-index --fsmonitor
'
if test -n "$GIT_PERF_7519_DROP_CACHE"; then
test-drop-caches
fi
test_perf "status (fsmonitor=$INTEGRATION_SCRIPT)" '
git status
'
if test -n "$GIT_PERF_7519_DROP_CACHE"; then
test-drop-caches
fi
test_perf "status -uno (fsmonitor=$INTEGRATION_SCRIPT)" '
git status -uno
'
if test -n "$GIT_PERF_7519_DROP_CACHE"; then
test-drop-caches
fi
test_perf "status -uall (fsmonitor=$INTEGRATION_SCRIPT)" '
git status -uall
'
test_expect_success "setup without fsmonitor" '
unset INTEGRATION_SCRIPT &&
git config --unset core.fsmonitor &&
git update-index --no-fsmonitor
'
if test -n "$GIT_PERF_7519_DROP_CACHE"; then
test-drop-caches
fi
test_perf "status (fsmonitor=$INTEGRATION_SCRIPT)" '
git status
'
if test -n "$GIT_PERF_7519_DROP_CACHE"; then
test-drop-caches
fi
test_perf "status -uno (fsmonitor=$INTEGRATION_SCRIPT)" '
git status -uno
'
if test -n "$GIT_PERF_7519_DROP_CACHE"; then
test-drop-caches
fi
test_perf "status -uall (fsmonitor=$INTEGRATION_SCRIPT)" '
git status -uall
'
if test_have_prereq WATCHMAN
then
watchman watch-del "$GIT_WORK_TREE" >/dev/null 2>&1 &&
# Work around Watchman bug on Windows where it holds on to handles
# preventing the removal of the trash directory
watchman shutdown-server >/dev/null 2>&1
fi
test_done