| Message ID | 1474968132-16196-1-git-send-email-petri.latvala@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Sep 27, 2016 at 12:22:12PM +0300, Petri Latvala wrote: > The drop_caches sysctl has a max value of 4, so writing 7 to it just > fails. Avoid the earlier two-writes problem by opening the fd twice. > > v2: Don't lseek(), open() twice. (Chris) > > Signed-off-by: Petri Latvala <petri.latvala@intel.com> Thanks, pushed. The sysctl being a bitmask and not accepting the full range is a bit surprising. -Chris
diff --git a/lib/intel_os.c b/lib/intel_os.c index b9f970d..e448bb4 100644 --- a/lib/intel_os.c +++ b/lib/intel_os.c @@ -299,11 +299,20 @@ void intel_purge_vm_caches(void) if (fd < 0) return; + /* BIT(2): Be quiet. Cannot be combined with other operations, + * the sysctl has a max value of 4. + */ + igt_ignore_warn(write(fd, "4\n", 2)); + close(fd); + + fd = open("/proc/sys/vm/drop_caches", O_WRONLY); + if (fd < 0) + return; + /* BIT(0): Drop page cache * BIT(1): Drop slab cache - * BIT(2): Be quiet in future */ - igt_ignore_warn(write(fd, "7\n", 2)); + igt_ignore_warn(write(fd, "3\n", 2)); close(fd); }
The drop_caches sysctl has a max value of 4, so writing 7 to it just fails. Avoid the earlier two-writes problem by opening the fd twice. v2: Don't lseek(), open() twice. (Chris) Signed-off-by: Petri Latvala <petri.latvala@intel.com> --- lib/intel_os.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)