Le 02/08/2017 à 10:10, Christophe LEROY a écrit :
Le 02/08/2017 à 09:31, Aneesh Kumar K.V a écrit :
Christophe LEROY <christophe.leroy@xxxxxx> writes:
Hi,
Le 28/07/2017 à 07:01, Aneesh Kumar K.V a écrit :
With commit aa888a74977a8 ("hugetlb: support larger than MAX_ORDER")
we added
support for allocating gigantic hugepages via kernel command line.
Switch
ppc64 arch specific code to use that.
W.r.t FSL support, we now limit our allocation range using
BOOTMEM_ALLOC_ACCESSIBLE.
We use the kernel command line to do reservation of hugetlb pages on
powernv
platforms. On pseries hash mmu mode the supported gigantic huge page
size is
16GB and that can only be allocated with hypervisor assist. For
pseries the
command line option doesn't do the allocation. Instead pseries does
gigantic
hugepage allocation based on hypervisor hint that is specified via
"ibm,expected#pages" property of the memory node.
It looks like it doesn't work on the 8xx:
root@vgoip:~# dmesg | grep -i huge
[ 0.000000] Kernel command line: console=ttyCPM0,115200N8
ip=172.25.231.25:172.25.231.1::255.0.0.0:vgoip:eth0:off hugepagesz=8M
hugepages=4
[ 0.416722] HugeTLB registered 8.00 MiB page size, pre-allocated 4
pages
[ 0.423184] HugeTLB registered 512 KiB page size, pre-allocated 0
pages
root@vgoip:~# cat /proc/meminfo
MemTotal: 123388 kB
MemFree: 77900 kB
MemAvailable: 78412 kB
Buffers: 0 kB
Cached: 3964 kB
SwapCached: 0 kB
Active: 3788 kB
Inactive: 1680 kB
Active(anon): 1636 kB
Inactive(anon): 20 kB
Active(file): 2152 kB
Inactive(file): 1660 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 1552 kB
Mapped: 2404 kB
Shmem: 152 kB
Slab: 0 kB
SReclaimable: 0 kB
SUnreclaim: 0 kB
KernelStack: 304 kB
PageTables: 208 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 45308 kB
Committed_AS: 16664 kB
VmallocTotal: 866304 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 512 kB
But you are printing above the default hugepaeg details. You haven't
changed that in kernel command line. What does
/sys/kernel/mm/hugepages/<hugepages-size>/nr_hugepages show ?
It says 4, so indeed it seems to work.
To change the default hugepage size you may want to use
default_hugepagesz=8M
Ah ? Documentation/admin-guide/kernel-parameters.txt says it is the same
as hugepagesz:
default_hugepagesz=
[same as hugepagesz=] The size of the default
HugeTLB page size. This is the size represented by
the legacy /proc/ hugepages APIs, used for SHM, and
default size when mounting hugetlbfs filesystems.
Defaults to the default architecture's huge page size
if not specified.
You are right, with default_hugepagesz instead of hugepagesz I get the
following in 16k page sizes mode (ie 8M is < MAX_ORDER)
root@vgoip:~# dmesg | grep -i huge
[ 0.000000] Kernel command line: console=ttyCPM0,115200N8
ip=172.25.231.25:172.25.231.1::255.0.0.0:vgoip:eth0:off
default_hugepagesz=8M hugepages=4
[ 0.410451] HugeTLB registered 512 KiB page size, pre-allocated 0 pages
[ 0.417091] HugeTLB registered 8.00 MiB page size, pre-allocated 4 pages
root@vgoip:~# cat /proc/meminfo
MemTotal: 123968 kB
MemFree: 73248 kB
MemAvailable: 75120 kB
Buffers: 0 kB
Cached: 5936 kB
SwapCached: 0 kB
Active: 6912 kB
Inactive: 2496 kB
Active(anon): 3664 kB
Inactive(anon): 80 kB
Active(file): 3248 kB
Inactive(file): 2416 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 3536 kB
Mapped: 3216 kB
Shmem: 272 kB
Slab: 0 kB
SReclaimable: 0 kB
SUnreclaim: 0 kB
KernelStack: 304 kB
PageTables: 672 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 45600 kB
Committed_AS: 18528 kB
VmallocTotal: 866304 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HugePages_Total: 4
HugePages_Free: 4
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 8192 kB
However, in 4K pages mode, ie (8M > MAX_ORDER), I get
root@vgoip:~# dmesg | grep -i huge
[ 0.000000] Kernel command line: console=ttyCPM0,115200N8
ip=172.25.231.25:172.25.231.1::255.0.0.0:vgoip:eth0:off
default_hugepagesz=8M hugepages=4
[ 0.413274] HugeTLB registered 512 KiB page size, pre-allocated 0 pages
[ 0.419844] HugeTLB registered 8.00 MiB page size, pre-allocated 0 pages
root@vgoip:~# cat /proc/meminfo
...
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 8192 kB
Looks like for gigantic pages, we have to specify both
default_hugepagesz=8M and hugepagesz=8M. When we do it it works back:
[ 0.000000] Kernel command line: console=ttyCPM0,115200N8
ip=172.25.231.25:172.25.231.1::255.0.0.0:vgoip:eth0:off
default_hugepagesz=8M hugepagesz=8M hugepages=4
[ 0.420093] HugeTLB registered 8.00 MiB page size, pre-allocated 4 pages
[ 0.426538] HugeTLB registered 512 KiB page size, pre-allocated 0 pages
Indeed it works even without your patch.
Christophe
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