----- Original Message -----
> From: "Zhouping Liu" <[email protected]>
> To: "shuang qiu" <[email protected]>
> Cc: [email protected]
> Sent: Friday, August 24, 2012 4:11:41 PM
> Subject: Re: [LTP] [PATCH] Set tunable value of min_free_kbytes lower
>
>
>
> ----- Original Message -----
> > From: "shuang qiu" <[email protected]>
> > To: [email protected]
> > Sent: Thursday, August 23, 2012 2:43:01 PM
> > Subject: [LTP] [PATCH] Set tunable value of min_free_kbytes lower
> >
> > From: Shuang Qiu <[email protected]>
> >
> > The value of min_free_kbytes is set too high(half of mem_free)
> > during
> > testing min_free_kbytes tunable.It often cause the system to become
> > out-of-memory.Using 20% of mem_free to avoid oom and system hang.
>
> Hi, shuang
>
> I met the issue that min_free_kbytes caused system hang before, and
> what you said made sense.
For the issue that min_free_kbytes caused system hang, I prepared a patch for
it,
at the same time, in order to enlarge the case's coverage, I add a new case(2x
default_tune)
I have tested it in my box, it's good.
Shuang, can you review and test the patch?
diff --git a/testcases/kernel/mem/tunable/min_free_kbytes.c
b/testcases/kernel/mem/tunable/min_free_kbytes.c
index 00ead04..ded0e45 100644
--- a/testcases/kernel/mem/tunable/min_free_kbytes.c
+++ b/testcases/kernel/mem/tunable/min_free_kbytes.c
@@ -10,7 +10,8 @@
* the current free memory with the tunable value repeatedly.
*
* a) default min_free_kbytes with all overcommit memory policy
- * b) half of mem_free with all overcommit memory policy
+ * b) 2x default value with all overcommit memory policy
+ * c) 10% of MemFree or %5 MemTotal with all overcommit memory policy
*
********************************************************************
* Copyright (C) 2012 Red Hat, Inc.
@@ -115,20 +116,27 @@ int main(int argc, char *argv[])
static void test_tune(unsigned long overcommit_policy)
{
int status;
- int pid[2];
+ int pid[3];
int ret, i;
- unsigned long tune, memfree;
+ unsigned long tune, memfree, memtotal;
set_sys_tune("overcommit_memory", overcommit_policy, 1);
- for (i = 0; i < 2; i++) {
+ for (i = 0; i < 3; i++) {
/* case1 */
if (i == 0)
set_sys_tune("min_free_kbytes", default_tune, 1);
/* case2 */
- else {
+ else if (i == 1) {
+ set_sys_tune("min_free_kbytes", 2 * default_tune, 1);
+ /* case3 */
+ } else {
memfree = read_meminfo("MemFree:");
- tune = memfree / 2;
+ memtotal = read_meminfo("MemTotal:");
+ tune = memfree / 10;
+ if (tune > (memtotal / 20))
+ tune = memtotal / 20;
+
set_sys_tune("min_free_kbytes", tune, 1);
}
>
> but after tested the patch, I found it still make the system hang
> with the patch, so I don't think
> this patch can fix the issue completely, maybe there are other
> factors, or need lower tune value.
> always suppose it was because of the high tune value, it's more
> better to add an optional to control it.
> also I will investigate it deeper to look after the real reason.
> please comment if you have other ideas.
>
> Thanks,
> Zhouping
>
> > ---
> > testcases/kernel/mem/tunable/min_free_kbytes.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/testcases/kernel/mem/tunable/min_free_kbytes.c
> > b/testcases/kernel/mem/tunable/min_free_kbytes.c
> > index 00ead04..8a03f85 100644
> > --- a/testcases/kernel/mem/tunable/min_free_kbytes.c
> > +++ b/testcases/kernel/mem/tunable/min_free_kbytes.c
> > @@ -128,7 +128,7 @@ static void test_tune(unsigned long
> > overcommit_policy)
> > /* case2 */
> > else {
> > memfree = read_meminfo("MemFree:");
> > - tune = memfree / 2;
> > + tune = memfree / 5;
> > set_sys_tune("min_free_kbytes", tune, 1);
> > }
> >
> > --
> > 1.7.7
> >
> >
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--
Thanks,
Zhouping
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