From: Mike Rapoport <rppt@linux.ibm.com>
To: Christophe LEROY <christophe.leroy@c-s.fr>
Cc: Michal Hocko <mhocko@suse.com>,
linux-sh@vger.kernel.org, linux-mm@kvack.org,
Rich Felker <dalias@libc.org>, Paul Mackerras <paulus@samba.org>,
sparclinux@vger.kernel.org, Vincent Chen <deanbo422@gmail.com>,
Jonas Bonn <jonas@southpole.se>,
linux-c6x-dev@linux-c6x.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Russell King <linux@armlinux.org.uk>,
Mark Salter <msalter@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
openrisc@lists.librecores.org, Greentime Hu <green.hu@gmail.com>,
Stafford Horne <shorne@gmail.com>, Guan Xuetao <gxt@pku.edu.cn>,
linux-arm-kernel@lists.infradead.org,
Michal Simek <monstr@monstr.eu>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH 5/5] arch: simplify several early memory allocations
Date: Mon, 26 Nov 2018 09:25:46 +0200 [thread overview]
Message-ID: <20181126072546.GB14863@rapoport-lnx> (raw)
In-Reply-To: <7a92357c-6251-fe84-d724-16fdc49d03a3@c-s.fr>
On Mon, Nov 26, 2018 at 08:03:55AM +0100, Christophe LEROY wrote:
>
>
> Le 25/11/2018 à 22:44, Mike Rapoport a écrit :
> >There are several early memory allocations in arch/ code that use
> >memblock_phys_alloc() to allocate memory, convert the returned physical
> >address to the virtual address and then set the allocated memory to zero.
> >
> >Exactly the same behaviour can be achieved simply by calling
> >memblock_alloc(): it allocates the memory in the same way as
> >memblock_phys_alloc(), then it performs the phys_to_virt() conversion and
> >clears the allocated memory.
> >
> >Replace the longer sequence with a simpler call to memblock_alloc().
> >
> >Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> >---
> > arch/arm/mm/mmu.c | 4 +---
> > arch/c6x/mm/dma-coherent.c | 9 ++-------
> > arch/nds32/mm/init.c | 12 ++++--------
> > arch/powerpc/kernel/setup-common.c | 4 ++--
> > arch/powerpc/mm/pgtable_32.c | 4 +---
> > arch/powerpc/mm/ppc_mmu_32.c | 3 +--
> > arch/powerpc/platforms/powernv/opal.c | 3 +--
> > arch/sparc/kernel/prom_64.c | 7 ++-----
> > arch/sparc/mm/init_64.c | 9 +++------
> > arch/unicore32/mm/mmu.c | 4 +---
> > 10 files changed, 18 insertions(+), 41 deletions(-)
> >
> [...]
>
> >diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> >index bda3c6f..9931e68 100644
> >--- a/arch/powerpc/mm/pgtable_32.c
> >+++ b/arch/powerpc/mm/pgtable_32.c
> >@@ -50,9 +50,7 @@ __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
> > if (slab_is_available()) {
> > pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
> > } else {
> >- pte = __va(memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE));
> >- if (pte)
> >- clear_page(pte);
> >+ pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
>
> memblock_alloc() uses memset to zeroize the block.
>
> clear_page() is more performant than memset().
As far as I can tell, the majority of the page table pages will be anyway
allocated with __get_free_page() so I think the performance loss here will
negligible.
> Christophe
>
> [...]
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2018-11-26 7:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-25 21:44 [PATCH 0/5] memblock: simplify several early memory allocations Mike Rapoport
2018-11-25 21:44 ` [PATCH 1/5] powerpc: prefer memblock APIs returning virtual address Mike Rapoport
2018-11-25 21:44 ` [PATCH 2/5] microblaze: prefer memblock API " Mike Rapoport
2018-11-25 21:44 ` [PATCH 3/5] sh: prefer memblock APIs " Mike Rapoport
2018-11-25 21:44 ` [PATCH 4/5] openrisc: simplify pte_alloc_one_kernel() Mike Rapoport
2018-11-27 21:16 ` Stafford Horne
2018-11-27 21:48 ` Mike Rapoport
2018-11-25 21:44 ` [PATCH 5/5] arch: simplify several early memory allocations Mike Rapoport
2018-11-26 7:03 ` Christophe LEROY
2018-11-26 7:25 ` Mike Rapoport [this message]
2018-11-26 8:21 ` Christoph Hellwig
2018-11-26 8:47 ` Mike Rapoport
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