[PATCH v2] RAS/CEC: Reduce offline page threshold for Intel systems

[Tony Luck <tony.luck@intel.com>]

A large scale study of memory errors on Intel systems in data centers
showed that aggressively taking pages with corrected errors offline is
the best strategy of using corrected errors as a predictor of future
uncorrected errors.

Set the threshold to "2" on Intel systems. AMD guidance is that this is
not necessary for their systems.

Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---

V2:
	Fix some spelling errors. 
	Add note to commit that AMD systems do not need this.
	Add Yazen's Reviewed-by tag.

 drivers/ras/cec.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index 42f2fc0bc8a9..321af498ee11 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -556,6 +556,14 @@ static int __init cec_init(void)
 	if (ce_arr.disabled)
 		return -ENODEV;
 
+	/*
+	 * Intel systems may avoid uncorrectable errors
+	 * if pages with corrected errors are aggressively
+	 * taken offline.
+	 */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+		action_threshold = 2;
+
 	ce_arr.array = (void *)get_zeroed_page(GFP_KERNEL);
 	if (!ce_arr.array) {
 		pr_err("Error allocating CE array page!\n");
-- 
2.35.3