From 3f4298427ad521fdc74fb991b17d84959513218a Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 7 Aug 2017 15:16:15 +0200 Subject: 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 Signed-off-by: Martin Schwidefsky --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Documentation/admin-guide') 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: -- cgit v1.2.3