From: Joel Fernandes <joel@joelfernandes.org>
To: David Miller <davem@davemloft.net>
Cc: kirill@shutemov.name, linux-kernel@vger.kernel.org,
kernel-team@android.com, minchan@kernel.org, pantin@google.com,
hughd@google.com, lokeshgidra@google.com, dancol@google.com,
mhocko@kernel.org, akpm@linux-foundation.org,
aryabinin@virtuozzo.com, luto@kernel.org, bp@alien8.de,
catalin.marinas@arm.com, chris@zankel.net,
dave.hansen@linux.intel.com, elfring@users.sourceforge.net,
fenghua.yu@intel.com, geert@linux-m68k.org, gxt@pku.edu.cn,
deller@gmx.de, mingo@redhat.com, jejb@parisc-linux.org,
jdike@addtoit.com, jonas@southpole.se, Julia.Lawall@lip6.fr,
kasan-dev@googlegroups.com, kvmarm@lists.cs.columbia.edu,
lftan@altera.com, linux-alpha@vger.kernel.org,
linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, linux-mips@linux-mips.orgl
Subject: Re: [PATCH v2 2/2] mm: speed up mremap by 500x on large regions
Date: Sat, 13 Oct 2018 01:35:40 +0000 [thread overview]
Message-ID: <20181013013540.GA207108@joelaf.mtv.corp.google.com> (raw)
In-Reply-To: <20181012.111836.1569129998592378186.davem@davemloft.net>
On Fri, Oct 12, 2018 at 11:18:36AM -0700, David Miller wrote:
> From: Joel Fernandes <joel@joelfernandes.org>
[...]
> > Also, do we not flush the caches from any path when we munmap
> > address space? We do call do_munmap on the old mapping from mremap
> > after moving to the new one.
>
> Sparc makes sure that shared mapping have consistent colors. Therefore
> all that's left are private mappings and those will be initialized by
> block stores to clear the page out or similar.
>
> Also, when creating new mappings, we flush the D-cache when necessary
> in update_mmu_cache().
>
> We also maintain a bit in the page struct to track when a page which
> was potentially written to on one cpu ends up mapped into another
> address space and flush as necessary.
>
> The cache is write-through, which simplifies the preconditions we have
> to maintain.
Makes sense, thanks. For the moment I sent patches to enable this on arm64
and x86. We can enable it on sparc as well at a later time as it sounds it
could be a safe optimization to apply to that architecture as well.
thanks,
- Joel
next prev parent reply other threads:[~2018-10-13 1:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181012013756.11285-1-joel@joelfernandes.org>
[not found] ` <20181012013756.11285-2-joel@joelfernandes.org>
[not found] ` <20181012113056.gxhcbrqyu7k7xnyv@kshutemo-mobl1>
2018-10-12 18:02 ` [PATCH v2 2/2] mm: speed up mremap by 500x on large regions David Miller
[not found] ` <20181012125046.GA170912@joelaf.mtv.corp.google.com>
2018-10-12 18:18 ` David Miller
2018-10-13 1:35 ` Joel Fernandes [this message]
2018-10-13 1:39 ` Daniel Colascione
2018-10-13 1:44 ` Joel Fernandes
2018-10-13 1:54 ` Daniel Colascione
2018-10-13 2:10 ` Joel Fernandes
2018-10-13 2:25 ` Daniel Colascione
2018-10-13 17:50 ` Joel Fernandes
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