Commit-ID: cbf74cea070fa1f705de4712e25d9e56ae6543c7
Gitweb: http://git.kernel.org/tip/cbf74cea070fa1f705de4712e25d9e56ae6543c7
Author: Robert Richter <robert.richter@xxxxxxx>
AuthorDate: Mon, 30 May 2011 16:31:11 +0200
Committer: Robert Richter <robert.richter@xxxxxxx>
CommitDate: Mon, 30 May 2011 16:36:54 +0200
oprofile, x86: Add comments to IBS LVT offset initialization
Adding a comment in the code as IBS LVT setup is not obvious at all ...
Signed-off-by: Robert Richter <robert.richter@xxxxxxx>
---
arch/x86/kernel/apic/apic.c | 3 ++-
arch/x86/oprofile/op_model_amd.c | 13 +++++++++----
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index fabf01e..a0bf78a 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -390,7 +390,8 @@ static unsigned int reserve_eilvt_offset(int offset, unsigned int new)
/*
* If mask=1, the LVT entry does not generate interrupts while mask=0
- * enables the vector. See also the BKDGs.
+ * enables the vector. See also the BKDGs. Must be called with
+ * preemption disabled.
*/
int setup_APIC_eilvt(u8 offset, u8 vector, u8 msg_type, u8 mask)
diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c
index 9fd8a56..9cbb710 100644
--- a/arch/x86/oprofile/op_model_amd.c
+++ b/arch/x86/oprofile/op_model_amd.c
@@ -609,16 +609,21 @@ static int setup_ibs_ctl(int ibs_eilvt_off)
return 0;
}
+/*
+ * This runs only on the current cpu. We try to find an LVT offset and
+ * setup the local APIC. For this we must disable preemption. On
+ * success we initialize all nodes with this offset. This updates then
+ * the offset in the IBS_CTL per-node msr. The per-core APIC setup of
+ * the IBS interrupt vector is called from op_amd_setup_ctrs()/op_-
+ * amd_cpu_shutdown() using the new offset.
+ */
static int force_ibs_eilvt_setup(void)
{
int offset;
int ret;
- /*
- * find the next free available EILVT entry, skip offset 0,
- * pin search to this cpu
- */
preempt_disable();
+ /* find the next free available EILVT entry, skip offset 0 */
for (offset = 1; offset < APIC_EILVT_NR_MAX; offset++) {
if (get_eilvt(offset))
break;
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|