On Fri, Oct 13, 2006 at 12:45:44PM -0700, Nishanth Aravamudan wrote:
> On 11.10.2006 [13:53:18 +1000], David Gibson wrote:
> > A couple of questions about the mlock testcase added in commit
> > ff2f5343e4a4e2d2e62173d557a7e5952cfa7733.
> >
> > First, is there a rationale for mlock()ing all the available hugepages
> > (as passed in on the command line). I don't see an obvious reason
> > that that's a useful thing to test (as opposed to just mlock()ing a
> > sample page), and it makes the testcase run quite slowly. I'd like to
> > keep the "functional" (rather than "stress") portion of the testsuite
> > nice and fast, making for quicker cycle time when tracking down
> > regressions.
> >
> > Second, the testcase maps the file both normally and with MAP_LOCKED,
> > which ought to lock the file as with mlock() at mmap() time. It also
> > explicitly mlock()s the file, but only when mapped with MAP_LOCKED
> > which seems backwards. Surely we should be checking mlock() when the
> > file was not originally locked. Is this really the intended
> > behaviour.
>
> Your concerns seem pretty valid, David.
>
> Patches are welcome :)
Here you go, then:
Simplify and speed up the mlock testcase.
At present the mlock test case attempts to mlock() all available
hugepages (as passed in on the command line). This isn't particularly
more useful than just testing locking a single page. This patch
reduces it to testing just a single page (with each set of mapping
options).
In addition, we were only testing actual mlock() calls on files opened
with MAP_LOCKED, which are supposed to be mlock()ed anyway, rather an
oversight. This patch corrects this also.
What would be another useful test is to verify that mlock()ing really
does reserve the page in question, i.e. that a page mlock()ed but not
touched will always instantiate without fault later, even if all other
hugepages on the system have been consumed. That's another patch for
another day.
Signed-off-by: David Gibson <[EMAIL PROTECTED]>
Index: libhugetlbfs/tests/mlock.c
===================================================================
--- libhugetlbfs.orig/tests/mlock.c 2006-09-04 17:08:33.000000000 +1000
+++ libhugetlbfs/tests/mlock.c 2006-10-16 11:41:22.000000000 +1000
@@ -29,46 +29,36 @@
#include <hugetlbfs.h>
#include "hugetests.h"
-static void test_simple_mlock(unsigned long size, unsigned long map_flags)
+static void test_simple_mlock(int flags)
{
- char *a;
- int ret;
int fd = hugetlbfs_unlinked_fd();
+ void *p;
+ int ret;
- a = mmap(0, size, PROT_READ|PROT_WRITE, map_flags, fd, 0);
- if (a == MAP_FAILED)
- FAIL("mmap() failed: %s", strerror(errno));
-
- if (map_flags & MAP_LOCKED) {
- ret = mlock(a, size);
- if (ret)
- FAIL("mlock() failed: %s", strerror(errno));
-
- ret = munlock(a, size);
- if (ret)
- FAIL("munlock() failed: %s", strerror(errno));
- }
+ p = mmap(0, gethugepagesize(), PROT_READ|PROT_WRITE, flags, fd, 0);
+ if (p == MAP_FAILED)
+ FAIL("mmap() failed (flags=%x): %s", flags, strerror(errno));
- ret = munmap(a, size);
+ ret = mlock(p, gethugepagesize());
if (ret)
- FAIL("munmap() failed: %s", strerror(errno));
+ FAIL("mlock() failed (flags=%x): %s", flags, strerror(errno));
+
+ ret = munlock(p, gethugepagesize());
+ if (ret)
+ FAIL("munlock() failed (flags=%x): %s", flags, strerror(errno));
+
+ ret = munmap(p, gethugepagesize());
+ if (ret)
+ FAIL("munmap() failed (flags=%x): %s", flags, strerror(errno));
close(fd);
}
int main(int argc, char *argv[])
{
- unsigned long tot_pages, size;
-
- if (argc != 2)
- CONFIG("Usage: mlock <# total available hugepages>");
-
- tot_pages = atoi(argv[1]);
- size = tot_pages * gethugepagesize();
-
- test_simple_mlock(size, MAP_PRIVATE);
- test_simple_mlock(size, MAP_SHARED);
- test_simple_mlock(size, MAP_PRIVATE|MAP_LOCKED);
- test_simple_mlock(size, MAP_SHARED|MAP_LOCKED);
+ test_simple_mlock(MAP_PRIVATE);
+ test_simple_mlock(MAP_SHARED);
+ test_simple_mlock(MAP_PRIVATE|MAP_LOCKED);
+ test_simple_mlock(MAP_SHARED|MAP_LOCKED);
PASS();
}
Index: libhugetlbfs/tests/run_tests.sh
===================================================================
--- libhugetlbfs.orig/tests/run_tests.sh 2006-10-16 11:17:10.000000000
+1000
+++ libhugetlbfs/tests/run_tests.sh 2006-10-16 11:25:06.000000000 +1000
@@ -109,7 +109,7 @@ functional_tests () {
run_test truncate
run_test shared
run_test mprotect
- run_test mlock `free_hpages`
+ run_test mlock
# Specific kernel bug tests
run_test ptrace-write-hugepage
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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