From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: Li Yang-R58472 <r58472@freescale•com>
Cc: linuxppc-dev@ozlabs•org
Subject: RE: [RFC] powerpc/mm: honor O_SYNC flag for memory map
Date: Fri, 20 Nov 2009 20:03:53 +1100 [thread overview]
Message-ID: <1258707833.2140.865.camel@pasglop> (raw)
In-Reply-To: <3A45394FD742FA419B760BB8D398F9EDCBC1F2@zch01exm26.fsl.freescale.net>
On Fri, 2009-11-20 at 11:00 +0800, Li Yang-R58472 wrote:
> Because there is no way to set mapped memory as cacheable if the
> memory
> is not managed by Linux kernel. While, it's not rare in real system
> to
> allocate some dedicated memory to a certain application which is not
> managed by kernel and then mmap'ed the memory to the application. The
> memory should be cacheable but we can't map it to be cacheable due to
> this intelligent setting. And it is a big hit to the performance.
> Moreover, the standard O_SYNC flag suggest that user has the control
> over cacheablity, but actually we had not.
You need to be a bit more careful tho. You must not allow RAM managed by
the kernel to be mapped non-cachable.
Cheers,
Ben.
next prev parent reply other threads:[~2009-11-20 9:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-17 7:10 [RFC] powerpc/mm: honor O_SYNC flag for memory map Li Yang
2009-11-19 13:55 ` Kumar Gala
2009-11-20 3:00 ` Li Yang-R58472
2009-11-20 9:03 ` Benjamin Herrenschmidt [this message]
2009-11-20 9:23 ` Li Yang
2009-11-21 20:01 ` Segher Boessenkool
2009-11-25 8:07 ` Li Yang
2009-11-25 11:30 ` Gabriel Paubert
2009-11-26 7:43 ` Li Yang
2009-11-27 2:30 ` Paul Mackerras
2009-11-30 10:00 ` Li Yang
2009-11-26 21:26 ` Segher Boessenkool
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