From: Mike Rapoport <rppt@linux.vnet.ibm.com>
To: Pintu Kumar <pintu.ping@gmail.com>
Cc: open list <linux-kernel@vger.kernel.org>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org
Subject: Re: KSM not working in 4.9 Kernel
Date: Sun, 16 Sep 2018 18:32:38 +0300 [thread overview]
Message-ID: <20180916153237.GC15699@rapoport-lnx> (raw)
In-Reply-To: <CAOuPNLj1wx4sznrtLdKjcvuTf0dECPWzPaR946FoYRXB6YAGCw@mail.gmail.com>
On Fri, Sep 14, 2018 at 07:58:01PM +0530, Pintu Kumar wrote:
> Hi All,
>
> Board: Hikey620 ARM64
> Kernel: 4.9.20
>
> I am trying to verify KSM (Kernel Same Page Merging) functionality on
> 4.9 Kernel using "mmap" and madvise user space test utility.
> But to my observation, it seems KSM is not working for me.
> CONFIG_KSM=y is enabled in kernel.
> ksm_init is also called during boot up.
> 443 ? SN 0:00 [ksmd]
>
> ksmd thread is also running.
>
> However, when I see the sysfs, no values are written.
> ~ # grep -H '' /sys/kernel/mm/ksm/*
> /sys/kernel/mm/ksm/pages_hashed:0
> /sys/kernel/mm/ksm/pages_scanned:0
> /sys/kernel/mm/ksm/pages_shared:0
> /sys/kernel/mm/ksm/pages_sharing:0
> /sys/kernel/mm/ksm/pages_to_scan:200
> /sys/kernel/mm/ksm/pages_unshared:0
> /sys/kernel/mm/ksm/pages_volatile:0
> /sys/kernel/mm/ksm/run:1
> /sys/kernel/mm/ksm/sleep_millisecs:1000
>
> So, please let me know if I am doing any thing wrong.
>
> This is the test utility:
> int main(int argc, char *argv[])
> {
> int i, n, size;
> char *buffer;
> void *addr;
>
> n = 100;
> size = 100 * getpagesize();
> for (i = 0; i < n; i++) {
> buffer = (char *)malloc(size);
> memset(buffer, 0xff, size);
> addr = mmap(NULL, size,
> PROT_READ | PROT_EXEC | PROT_WRITE,
> MAP_PRIVATE | MAP_ANONYMOUS,
> -1, 0);
> madvise(addr, size, MADV_MERGEABLE);
Just mmap'ing an area does not allocate any physical pages, so KSM has
nothing to merge.
You need to memset(addr,...) after mmap().
> sleep(1);
> }
> printf("Done....press ^C\n");
>
> pause();
>
> return 0;
> }
>
>
>
> Thanks,
> Pintu
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2018-09-16 15:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 14:28 KSM not working in 4.9 Kernel Pintu Kumar
2018-09-14 17:12 ` Yang Shi
2018-09-15 2:55 ` Pintu Kumar
2018-09-16 15:32 ` Mike Rapoport [this message]
2018-09-16 17:05 ` Pintu Kumar
2018-09-17 4:37 ` Mike Rapoport
2018-09-17 6:16 ` Pintu Kumar
2018-09-17 11:55 ` Pintu Kumar
2018-09-17 14:59 ` Mike Rapoport
2018-09-20 11:51 ` Pintu Kumar
2018-09-21 8:16 ` Mike Rapoport
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