Commit 127493d5 authored by Nishanth Aravamudan's avatar Nishanth Aravamudan Committed by Benjamin Herrenschmidt
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powerpc/pseries: Use a kmem cache for DTL buffers

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 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.
Signed-off-by: default avatarBenjamin Herrenschmidt <>
parent 7c7a81b5
......@@ -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,
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,
dtl = kmem_cache_alloc(dtl_cache, GFP_KERNEL);
if (!dtl) {
pr_warn("Failed to allocate dispatch trace log for cpu %d\n",
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