From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Tabi Timur-B04825 <B04825@freescale.com>
Cc: Wood Scott-B07421 <B07421@freescale.com>,
Hu Mingkai-B21284 <B21284@freescale.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Xie Shaohui-B21989 <B21989@freescale.com>,
Chen Yuanquan-B41889 <B41889@freescale.com>
Subject: Re: [PATCH] powerpc/mm: add ZONE_NORMAL zone for 64 bit kernel
Date: Tue, 24 Jul 2012 14:45:57 +1000 [thread overview]
Message-ID: <1343105157.3715.6.camel@pasglop> (raw)
In-Reply-To: <500E1EB3.6060203@freescale.com>
On Tue, 2012-07-24 at 04:04 +0000, Tabi Timur-B04825 wrote:
> Benjamin Herrenschmidt wrote:
> > Sure but I don't want to create the zones in the first place (and thus
> > introduce the added pressure on the memory management) on machines that
> > don't need it.
>
> One thing that does confuse me -- by default, we don't create a
> ZONE_NORMAL. We only create a ZONE_DMA. Why is that? Shouldn't it be
> the other way around?
Because ZONE_NORMAL allocations can be serviced from the ZONE_DMA while
the other way isn't possible.
Especially in the old days, there were quite a few cases of drivers
and/or subsystems who were a bit heavy handed at using ZONE_DMA, so not
having one would essentially make them not work at all.
Cheers,
Ben.
next prev parent reply other threads:[~2012-07-24 4:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-20 12:21 [PATCH] powerpc/mm: add ZONE_NORMAL zone for 64 bit kernel Shaohui Xie
2012-07-23 6:06 ` Benjamin Herrenschmidt
2012-07-23 16:17 ` Scott Wood
2012-07-23 22:20 ` Benjamin Herrenschmidt
2012-07-23 23:08 ` Tabi Timur-B04825
2012-07-23 23:12 ` Benjamin Herrenschmidt
2012-07-23 23:15 ` Timur Tabi
2012-07-23 23:29 ` Benjamin Herrenschmidt
2012-07-23 23:30 ` Benjamin Herrenschmidt
2012-07-24 1:37 ` Scott Wood
2012-07-23 23:36 ` Timur Tabi
2012-07-24 3:08 ` Benjamin Herrenschmidt
2012-07-24 3:52 ` Tabi Timur-B04825
2012-07-24 3:59 ` Zang Roy-R61911
2012-07-24 4:04 ` Tabi Timur-B04825
2012-07-24 4:45 ` Benjamin Herrenschmidt [this message]
2012-07-24 8:01 ` Bhushan Bharat-R65777
2012-07-24 1:49 ` Scott Wood
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