On Tue, Jan 21, 2014 at 10:23:51AM +0000, Mel Gorman wrote: > On Tue, Jan 21, 2014 at 05:38:59PM +0800, Han Pingtian wrote: > > The testcase 'thp04' of LTP will enable THP, do some testing, then > > disable it if it wasn't enabled. But this will leave a different value > > of min_free_kbytes if it has been set by admin. So I think it's better > > to restore the user defined value after disabling THP. > > > > Then have LTP record what min_free_kbytes was at the same time THP was > enabled by the test and restore both settings. It leaves a window where > an admin can set an alternative value during the test but that would also > invalidate the test in same cases and gets filed under "don't do that". >
Because the value is changed in kernel, so it would be better to restore it in kernel, right? :) I have a v2 patch which will restore the value only if it isn't set again by user after THP's initialization. This v2 patch is dependent on the patch 'mm: show message when updating min_free_kbytes in thp' which has been added to -mm tree, can be found here: http://ozlabs.org/~akpm/mmotm/broken-out/mm-show-message-when-updating-min_free_kbytes-in-thp.patch please have a look. Thanks. >From 8b79586ff9a1d85cbe45102a86888268094ec0ae Mon Sep 17 00:00:00 2001 From: Han Pingtian <ha...@linux.vnet.ibm.com> Date: Tue, 21 Jan 2014 17:24:43 +0800 Subject: [PATCH] mm: restore user defined min_free_kbytes when disabling thp thp increases the value of min_free_kbytes in initialization. This will change the user defined value of min_free_kbytes sometimes. So try to restore the value when disabling thp if the value has been changed in thp initialization and isn't changed by user afte that. Signed-off-by: Han Pingtian <ha...@linux.vnet.ibm.com> --- mm/huge_memory.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 94a824f..fcb8ce58 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -164,6 +164,16 @@ static int start_khugepaged(void) } else if (khugepaged_thread) { kthread_stop(khugepaged_thread); khugepaged_thread = NULL; + + if (user_min_free_kbytes >= 0 && + user_min_free_kbytes != min_free_kbytes) { + pr_info("restore min_free_kbytes from %d to user " + "defined %d when stopping khugepaged\n", + min_free_kbytes, user_min_free_kbytes); + + min_free_kbytes = user_min_free_kbytes; + setup_per_zone_wmarks(); + } } return err; -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
