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Date: Mon, 30 May 2016 15:31:06 +1000
From: Anton Blanchard <anton@samba.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Aneesh Kumar K.V\"  <aneesh.kumar@linux.vnet.ibm.com>,
 paulus@samba.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
 Michael Neuling <mikey@neuling.org>
Subject: Re: [PATCH V2 04/68] powerpc/mm: Use big endian page table for
 book3s 64
Message-ID: <20160530153106.7ece1ca0@kryten>
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Hi,

> I see the same issue in unmap_page_range(), __hash_page_64K(),
> handle_mm_fault().

This looks to be about 10% slower on POWER8:

#include <stdlib.h>
#include <sys/mman.h>
#include <assert.h>

#define ITERATIONS 10000000

#define MEMSIZE (128 * 1024 * 1024)

int main(void)
{
        unsigned long i = ITERATIONS;

        while (i--) {
                char *c = mmap(NULL, MEMSIZE, PROT_READ|PROT_WRITE,
                               MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
                assert(c != MAP_FAILED);
                munmap(c, MEMSIZE);
        }

        return 0;
}