From: Christophe LEROY <christophe.leroy@c-s.fr>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Scott Wood <oss@buserror.net>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 5/5] powerpc/mm: Fix growth direction for hugepages mmaps with slice
Date: Wed, 24 Jan 2018 11:03:07 +0100 [thread overview]
Message-ID: <03c7f5ce-c2ed-7038-3a8b-3bb7a9a4a2dc@c-s.fr> (raw)
In-Reply-To: <47bbd8be-7b2e-245b-08d9-24958eec2ed2@linux.vnet.ibm.com>
Le 24/01/2018 à 10:51, Aneesh Kumar K.V a écrit :
>
>
> On 01/24/2018 03:09 PM, Christophe LEROY wrote:
>>
>>
>> Le 24/01/2018 à 10:35, Aneesh Kumar K.V a écrit :
>>>
>
>>>> Did you try with HUGETLB_MORECORE_HEAPBASE=0x11000000 on PPC64 as I
>>>> suggested in my last email on this subject (22/01/2018 9:22) ?
>>>
>>>
>>> yes. The test ran fine for me
>>
>> You tried with 0x30000000, it works as well on PPC32.
>>
>> I'd really like you to try with 0x11000000 which is in the same slice
>> as the 10020000-10030000 range.
>>
>>
>
> Now that explains is better. But then the requested HEAPBASE was not
> free and hence topdown search got an address in the below range.
>
> 7efffd000000-7f0000000000 rw-p 00000000 00:0d 1082770 /anon_hugepage
> (deleted)
>
>
> The new range allocated is such that there is no scope for expansion of
> heap if we do a topdown search. But why should that require us to change
> from topdown/bottomup search?
>
>
> 10000000-10010000 r-xp 00000000 fc:00 9044312 /home/kvaneesh/a.out
> 10010000-10020000 r--p 00000000 fc:00 9044312 /home/kvaneesh/a.out
> 10020000-10030000 rw-p 00010000 fc:00 9044312 /home/kvaneesh/a.out
> 7efffd000000-7f0000000000 rw-p 00000000 00:0d 1082770 /anon_hugepage
> (deleted)
> 7ffff2d40000-7ffff7d60000 rw-p 00000000 00:00 0
> 7ffff7d60000-7ffff7f10000 r-xp 00000000 fc:00 9250090
> /lib/powerpc64le-linux-gnu/libc-2.23.so
> 7ffff7f10000-7ffff7f20000 r--p 001a0000 fc:00 9250090
> /lib/powerpc64le-linux-gnu/libc-2.23.so
> 7ffff7f20000-7ffff7f30000 rw-p 001b0000 fc:00 9250090
> /lib/powerpc64le-linux-gnu/libc-2.23.so
> 7ffff7f40000-7ffff7f60000 r-xp 00000000 fc:00 10754812
> /usr/lib/libhugetlbfs.so.0
> 7ffff7f60000-7ffff7f70000 r--p 00010000 fc:00 10754812
> /usr/lib/libhugetlbfs.so.0
> 7ffff7f70000-7ffff7f80000 rw-p 00020000 fc:00 10754812
> /usr/lib/libhugetlbfs.so.0
> 7ffff7f80000-7ffff7fa0000 r-xp 00000000 00:00 0 [vdso]
> 7ffff7fa0000-7ffff7fe0000 r-xp 00000000 fc:00 9250107
> /lib/powerpc64le-linux-gnu/ld-2.23.so
> 7ffff7fe0000-7ffff7ff0000 r--p 00030000 fc:00 9250107
> /lib/powerpc64le-linux-gnu/ld-2.23.so
> 7ffff7ff0000-7ffff8000000 rw-p 00040000 fc:00 9250107
> /lib/powerpc64le-linux-gnu/ld-2.23.so
> 7ffffffd0000-800000000000 rw-p 00000000 00:00 0 [stack]
>
>
> For the specific test, one should pass the HEAPBASE value such that it
> can be expanded if required isn't it ?
For the test, yes, it is dumb to pass an unusable HEAPBASE, but what
happens in real life:
* PPC32: No HEAPBASE, hugetlbfs defines a HEAPBASE at sbrk(0) +
PAGE_SIZE = 0x10800000 ==> This is in the same slice as already
allocated ==> the kernel does as if mmap() had been called with no hint
address and allocates something unusable instead.
* PPC64: No HEAPBASE, hugetlbfs seems to define a HEAPBASE at
100000000000, which doesn't conflict with an already allocated mapping
==> it works.
Now, when we take the generic case, ie when slice is not activated, when
you call mmap() without a hint address, it allocates a suitable address
because it does bottom-up. Why do differently with slices ?
Christophe
next prev parent reply other threads:[~2018-01-24 10:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-24 9:02 [PATCH v3 1/5] powerpc/mm: Remove intermediate bitmap copy in 'slices' Christophe Leroy
2018-01-24 9:02 ` [PATCH v3 2/5] powerpc/mm: Enhance 'slice' for supporting PPC32 Christophe Leroy
2018-01-24 9:02 ` [PATCH v3 3/5] powerpc/32: Fix hugepage allocation on 8xx at hint address Christophe Leroy
2018-01-24 9:02 ` [PATCH v3 4/5] powerpc/mm: Allow up to 64 low slices Christophe Leroy
2018-01-29 6:29 ` Aneesh Kumar K.V
2018-01-29 8:56 ` Christophe LEROY
2018-02-10 12:58 ` Christophe LEROY
2018-01-24 9:02 ` [PATCH v3 5/5] powerpc/mm: Fix growth direction for hugepages mmaps with slice Christophe Leroy
2018-01-24 9:15 ` Aneesh Kumar K.V
2018-01-24 9:27 ` Christophe LEROY
2018-01-24 9:35 ` Aneesh Kumar K.V
2018-01-24 9:39 ` Christophe LEROY
2018-01-24 9:51 ` Aneesh Kumar K.V
2018-01-24 10:03 ` Christophe LEROY [this message]
2018-01-24 10:08 ` Aneesh Kumar K.V
2018-01-24 10:19 ` Christophe LEROY
2018-01-29 6:17 ` [PATCH v3 1/5] powerpc/mm: Remove intermediate bitmap copy in 'slices' Aneesh Kumar K.V
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=03c7f5ce-c2ed-7038-3a8b-3bb7a9a4a2dc@c-s.fr \
--to=christophe.leroy@c-s.fr \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=benh@kernel.crashing.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=oss@buserror.net \
--cc=paulus@samba.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).