fix merge conflict

3 files changed, 42 insertions, 0 deletions

diff --git a/open_issues/performance/io_system/binutils_ld_64ksec.mdwn b/open_issues/performance/io_system/binutils_ld_64ksec.mdwn
index 359d5fee..d0b8ea7f 100644
--- a/open_issues/performance/io_system/binutils_ld_64ksec.mdwn
+++ b/open_issues/performance/io_system/binutils_ld_64ksec.mdwn
@@ -27,6 +27,10 @@ extracted from cdf7c161ebd4a934c9e705d33f5247fd52975612 sources, 2010-10-24.
 On the idle grubber, this one repeatedly takes a few minutes wall time to
 complete successfully, contrary to a few seconds on a GNU/Linux system.
 
+> On order of slowness may in fact be due to a Xen-specific issue, see
+> [[xen_lseek]].  (But there are probably still one or two orders left, even
+> without Xen.)
+
 While processing the object files, there is heavy interaction with the relevant
 [[hurd/translator/ext2fs]] process.  Running [[hurd/debugging/rpctrace]] on
 the testee shows that (primarily) an ever-repeating series of `io_seek` and
@@ -47,4 +51,6 @@ IRC, freenode, #hurd, 2011-09-01:
     <youpi> (fgetpos actually, but that's the same)
     <youpi> and it is indeed about 10 times slower under Xen for some reason
 
+Also see testcase [[test-lseek.c]] and [[test-mach.c]]
+
 [[!tag open_issue_xen]]
diff --git a/open_issues/performance/io_system/test-lseek.c b/open_issues/performance/io_system/test-lseek.c
new file mode 100644
index 00000000..667dce66
--- /dev/null
+++ b/open_issues/performance/io_system/test-lseek.c
@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include <math.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/time.h>
+#define N 100000
+int main(void) {
+	int fd = open("test.c", O_RDONLY);
+	struct timeval tv1, tv2;
+	int i;
+	gettimeofday(&tv1, NULL);
+	for (i = 0; i < N; i++)
+		lseek(fd, 0, SEEK_CUR);
+	gettimeofday(&tv2, NULL);
+	printf("%fµs\n", (float)((tv2.tv_sec-tv1.tv_sec) * 1000000 + tv2.tv_usec - tv1.tv_usec)/N);
+	return 0;
+}
diff --git a/open_issues/performance/io_system/test-mach.c b/open_issues/performance/io_system/test-mach.c
new file mode 100644
index 00000000..90337346
--- /dev/null
+++ b/open_issues/performance/io_system/test-mach.c
@@ -0,0 +1,19 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <fcntl.h>
+#include <mach/mach.h>
+#define N 1000000
+int main(void) {
+	struct timeval tv1, tv2;
+	int i;
+	task_t task;
+	task = mach_task_self();
+	mach_port_urefs_t refs;
+	gettimeofday(&tv1, NULL);
+	for (i = 0; i < N; i++) {
+		mach_port_get_refs(task, task, MACH_PORT_RIGHT_RECEIVE, &refs);
+	}
+	gettimeofday(&tv2, NULL);
+	printf("%fµs\n", (float)((tv2.tv_sec-tv1.tv_sec) * 1000000 + tv2.tv_usec - tv1.tv_usec)/N);
+	return 0;
+}