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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2017-08-07 15:16:15 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-08-09 15:09:35 +0200 |
| commit | 3f4298427ad521fdc74fb991b17d84959513218a (patch) | |
| tree | c4a9cff2e5ac1261c745b74dc3a70a644fd448bd /Documentation/admin-guide | |
| parent | s390/cpcmd,vmcp: avoid GFP_DMA allocations (diff) | |
| download | linux-3f4298427ad521fdc74fb991b17d84959513218a.tar.xz linux-3f4298427ad521fdc74fb991b17d84959513218a.zip | |
s390/vmcp: make use of contiguous memory allocator
If memory is fragmented it is unlikely that large order memory
allocations succeed. This has been an issue with the vmcp device
driver since a long time, since it requires large physical contiguous
memory ares for large responses.
To hopefully resolve this issue make use of the contiguous memory
allocator (cma). This patch adds a vmcp specific vmcp cma area with a
default size of 4MB. The size can be changed either via the
VMCP_CMA_SIZE config option at compile time or with the "vmcp_cma"
kernel parameter (e.g. "vmcp_cma=16m").
For any vmcp response buffers larger than 16k memory from the cma area
will be allocated. If such an allocation fails, there is a fallback to
the buddy allocator.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index d9c171ce4190..5a2d5079139b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4375,6 +4375,10 @@ decrease the size and leave more room for directly mapped kernel RAM. + vmcp_cma=nn[MG] [KNL,S390] + Sets the memory size reserved for contiguous memory + allocations for the vmcp device driver. + vmhalt= [KNL,S390] Perform z/VM CP command after system halt. Format: <command> |