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[PATCH] Implement getloadavg()
- From: Jon Turney <jon dot turney at dronecode dot org dot uk>
- To: cygwin-patches at cygwin dot com
- Cc: Jon Turney <jon dot turney at dronecode dot org dot uk>
- Date: Fri, 17 Mar 2017 17:50:32 +0000
- Subject: [PATCH] Implement getloadavg()
- Authentication-results: sourceware.org; auth=none
Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>
---
winsup/cygwin/Makefile.in | 5 +-
winsup/cygwin/common.din | 1 +
winsup/cygwin/fhandler_proc.cc | 10 ++-
winsup/cygwin/include/cygwin/stdlib.h | 4 +
winsup/cygwin/include/cygwin/version.h | 3 +-
winsup/cygwin/loadavg.cc | 135 +++++++++++++++++++++++++++++++++
winsup/doc/posix.xml | 1 +
7 files changed, 154 insertions(+), 5 deletions(-)
create mode 100644 winsup/cygwin/loadavg.cc
diff --git a/winsup/cygwin/Makefile.in b/winsup/cygwin/Makefile.in
index c8652b0..5e719a6 100644
--- a/winsup/cygwin/Makefile.in
+++ b/winsup/cygwin/Makefile.in
@@ -147,7 +147,9 @@ EXTRA_OFILES:=
MALLOC_OFILES:=malloc.o
-DLL_IMPORTS:=${shell $(CC) -print-file-name=w32api/libkernel32.a} ${shell $(CC) -print-file-name=w32api/libntdll.a}
+DLL_IMPORTS:=${shell $(CC) -print-file-name=w32api/libkernel32.a} \
+ ${shell $(CC) -print-file-name=w32api/libntdll.a} \
+ ${shell $(CC) -print-file-name=w32api/libpdh.a}
MT_SAFE_OBJECTS:=
#
@@ -323,6 +325,7 @@ DLL_OFILES:= \
kernel32.o \
ldap.o \
libstdcxx_wrapper.o \
+ loadavg.o \
localtime.o \
lsearch.o \
malloc_wrapper.o \
diff --git a/winsup/cygwin/common.din b/winsup/cygwin/common.din
index f236813..8e54a7d 100644
--- a/winsup/cygwin/common.din
+++ b/winsup/cygwin/common.din
@@ -624,6 +624,7 @@ gethostname = cygwin_gethostname SIGFE
getifaddrs SIGFE
getitimer SIGFE
getline = __getline SIGFE
+getloadavg SIGFE
getlogin NOSIGFE
getlogin_r NOSIGFE
getmntent SIGFE
diff --git a/winsup/cygwin/fhandler_proc.cc b/winsup/cygwin/fhandler_proc.cc
index 2a8cf14..a7e816f 100644
--- a/winsup/cygwin/fhandler_proc.cc
+++ b/winsup/cygwin/fhandler_proc.cc
@@ -418,7 +418,7 @@ static off_t
format_proc_loadavg (void *, char *&destbuf)
{
extern int get_process_state (DWORD dwProcessId);
- unsigned running = 0;
+ unsigned int running = 0;
winpids pids ((DWORD) 0);
for (unsigned i = 0; i < pids.npids; i++)
@@ -429,9 +429,13 @@ format_proc_loadavg (void *, char *&destbuf)
break;
}
+ double loadavg[3] = { 0.0, 0.0, 0.0 };
+ getloadavg (loadavg, 3);
+
destbuf = (char *) crealloc_abort (destbuf, 48);
- return __small_sprintf (destbuf, "%u.%02u %u.%02u %u.%02u %u/%u\n",
- 0, 0, 0, 0, 0, 0, running, pids.npids);
+ return sprintf (destbuf, "%.2f %.2f %.2f %u/%u\n",
+ loadavg[0], loadavg[1], loadavg[2], running,
+ (unsigned int)pids.npids);
}
static off_t
diff --git a/winsup/cygwin/include/cygwin/stdlib.h b/winsup/cygwin/include/cygwin/stdlib.h
index 744a08d..a8eb4de 100644
--- a/winsup/cygwin/include/cygwin/stdlib.h
+++ b/winsup/cygwin/include/cygwin/stdlib.h
@@ -77,6 +77,10 @@ extern _PTR valloc _PARAMS ((size_t));
#undef _mstats_r
#define _mstats_r(r, p) mstats (p)
+#if __BSD_VISIBLE
+int getloadavg(double loadavg[], int nelem);
+#endif
+
#ifdef __cplusplus
}
#endif
diff --git a/winsup/cygwin/include/cygwin/version.h b/winsup/cygwin/include/cygwin/version.h
index 6ca3079..298741a 100644
--- a/winsup/cygwin/include/cygwin/version.h
+++ b/winsup/cygwin/include/cygwin/version.h
@@ -473,12 +473,13 @@ details. */
306: Export getentropy, getrandom.
307: Export timingsafe_bcmp, timingsafe_memcmp.
308: Export dladdr.
+ 309: Export getloadavg.
Note that we forgot to bump the api for ualarm, strtoll, strtoull,
sigaltstack, sethostname. */
#define CYGWIN_VERSION_API_MAJOR 0
-#define CYGWIN_VERSION_API_MINOR 308
+#define CYGWIN_VERSION_API_MINOR 309
/* There is also a compatibity version number associated with the shared memory
regions. It is incremented when incompatible changes are made to the shared
diff --git a/winsup/cygwin/loadavg.cc b/winsup/cygwin/loadavg.cc
new file mode 100644
index 0000000..63d8b3e
--- /dev/null
+++ b/winsup/cygwin/loadavg.cc
@@ -0,0 +1,135 @@
+/* loadavg.cc: load average support.
+
+ This file is part of Cygwin.
+
+ This software is a copyrighted work licensed under the terms of the
+ Cygwin license. Please consult the file "CYGWIN_LICENSE" for
+ details. */
+
+/*
+ Emulate load average
+
+ There's a fair amount of approximation done here, so don't try to use this to
+ actually measure anything, but it should be good enough for programs to
+ throttle their activity based on load.
+
+ A per-process load average estimate is maintained. This estimate is only
+ updated at most every 5 seconds.
+
+ We attempt to count running and runnable processes, but unlike linux we don't
+ count processes in uninterruptible sleep (blocked on I/O).
+
+ The number of running processes is estimated as (NumberOfProcessors) * (%
+ Processor Time). The number of runnable processes is estimated as
+ ProcessorQueueLength.
+
+ Note that PDH will only return data for '% Processor Time' afer the second
+ call to PdhCollectQueryData(), as it's computed over an interval, so the first
+ load estimate will always be 0.
+*/
+
+#include <math.h>
+#include <time.h>
+#include <sys/strace.h>
+
+#define _WIN32_WINNT 0x0600
+#include <pdh.h>
+
+static double _loadavg[3] = { 0.0, 0.0, 0.0 };
+static PDH_HQUERY query;
+static PDH_HCOUNTER counter1;
+static PDH_HCOUNTER counter2;
+
+static bool load_init (void)
+{
+ static bool tried = false;
+ static bool initialized = false;
+
+ if (!tried) {
+ tried = true;
+
+ if ((PdhOpenQueryA (NULL, 0, &query) == ERROR_SUCCESS) &&
+ (PdhAddEnglishCounterA (query, "\\Processor(_Total)\\% Processor Time",
+ 0, &counter1) == ERROR_SUCCESS) &&
+ (PdhAddEnglishCounterA (query, "\\System\\Processor Queue Length",
+ 0, &counter2) == ERROR_SUCCESS)) {
+ initialized = true;
+ } else {
+ debug_printf("loadavg PDH initialization failed\n");
+ }
+ }
+
+ return initialized;
+}
+
+/* estimate the current load */
+static double load (void)
+{
+ PDH_STATUS ret = PdhCollectQueryData (query);
+ if (ret != ERROR_SUCCESS)
+ return 0.0;
+
+ /* Estimate the number of running processes as (NumberOfProcessors) * (%
+ Processor Time) */
+ PDH_FMT_COUNTERVALUE fmtvalue1;
+ ret = PdhGetFormattedCounterValue (counter1, PDH_FMT_DOUBLE, NULL, &fmtvalue1);
+ if (ret != ERROR_SUCCESS)
+ return 0.0;
+
+ SYSTEM_INFO sysinfo;
+ GetSystemInfo (&sysinfo);
+
+ double running = fmtvalue1.doubleValue * sysinfo.dwNumberOfProcessors / 100;
+
+ /* Estimate the number of runnable processes using ProcessorQueueLength */
+ PDH_FMT_COUNTERVALUE fmtvalue2;
+ ret = PdhGetFormattedCounterValue (counter2, PDH_FMT_LONG, NULL, &fmtvalue2);
+ if (ret != ERROR_SUCCESS)
+ return 0.0;
+
+ LONG rql = fmtvalue2.longValue;
+
+ return rql + running;
+}
+
+static void calc_load (int index, int delta_time, int decay_time, double n)
+{
+ double df = 1.0 / exp ((double)delta_time/decay_time);
+ _loadavg[index] = (_loadavg[index] * df) + (n * (1.0 - df));
+}
+
+static void update_loadavg (int delta_time)
+{
+ if (!load_init ())
+ return;
+
+ double active_tasks = load ();
+
+ /* Compute the exponentially weighted moving average over ... */
+ calc_load (0, delta_time, 60, active_tasks); /* ... 1 min */
+ calc_load (1, delta_time, 300, active_tasks); /* ... 5 min */
+ calc_load (2, delta_time, 900, active_tasks); /* ... 15 min */
+}
+
+/* getloadavg: BSD */
+extern "C" int
+getloadavg (double loadavg[], int nelem)
+{
+ /* Don't recalculate the load average if less than 5 seconds has elapsed since
+ the last time it was calculated */
+ static time_t last_time = 0;
+ time_t curr_time = time (NULL);
+ int delta_time = curr_time - last_time;
+ if (delta_time >= 5) {
+ last_time = curr_time;
+ update_loadavg (delta_time);
+ }
+
+ /* The maximum number of samples is 3 */
+ if (nelem > 3)
+ nelem = 3;
+
+ /* Return the samples and number of samples retrieved */
+ memcpy (loadavg, _loadavg, nelem * sizeof(double));
+ return nelem;
+}
diff --git a/winsup/doc/posix.xml b/winsup/doc/posix.xml
index 03d168d..a3b2e9f 100644
--- a/winsup/doc/posix.xml
+++ b/winsup/doc/posix.xml
@@ -1173,6 +1173,7 @@ also IEEE Std 1003.1-2008 (POSIX.1-2008).</para>
getdtablesize
getgrouplist
getifaddrs
+ getloadavg
getpagesize
getpeereid
getprogname
--
2.8.3