PAPR specifies that DTL buffers can not cross AMS environments (aka CMO
in the PAPR) and can not cross a memory entitlement granule boundary
(4k). This is found in section 14.11.3.2 H_REGISTER_VPA of the PAPR.
kmalloc does not guarantee an alignment of the allocation, though,
beyond 8 bytes (at least in my understanding). Create a special kmem
cache for DTL buffers with the alignment requirement.
---
Change from v1: removed extraneous #include.
Change from v2: instead of overallocating and aligning, use a kmem cache
Change from v3: handle cache creation failure
Note, I initially put this in a firmware check if-block, but we have
also seen some issues with alignment with non-AMS partitions. The wasted
memory is unfortunate, though.
Signed-off-by: Nishanth Aravamudan <n...@us.ibm.com>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Ben Herrenschmidt <b...@kernel.crashing.org>
Cc: Anton Blanchard <an...@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
arch/powerpc/platforms/pseries/setup.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/setup.c
b/arch/powerpc/platforms/pseries/setup.c
index 0007241..9e20b83 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -287,14 +287,22 @@ static int alloc_dispatch_logs(void)
int cpu, ret;
struct paca_struct *pp;
struct dtl_entry *dtl;
+ struct kmem_cache *dtl_cache;
if (!firmware_has_feature(FW_FEATURE_SPLPAR))
return 0;
+ dtl_cache = kmem_cache_create("dtl", DISPATCH_LOG_BYTES,
+ DISPATCH_LOG_BYTES, 0, NULL);
+ if (!dtl_cache) {
+ pr_warn("Failed to create dispatch trace log buffer cache\n");
+ pr_warn("Stolen time statistics will be unreliable\n");
+ return 0;
+ }
+
for_each_possible_cpu(cpu) {
pp = &paca[cpu];
- dtl = kmalloc_node(DISPATCH_LOG_BYTES, GFP_KERNEL,
- cpu_to_node(cpu));
+ dtl = kmem_cache_alloc(dtl_cache, GFP_KERNEL);
if (!dtl) {
pr_warn("Failed to allocate dispatch trace log for cpu
%d\n",
cpu);
--
1.7.4.1
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