From: Frithiof Jensen <[email protected]>
This patch is meant for Kernel version 2.6.19
This is an attempt of providing an interface for memory
scrubbing control in EDAC.
This patch modifies the EDAC Core to provide the Interface
for memory controller modules to implment.
The following things are still outstanding:
- K8 is the first implemenation,
The patch provide a method of configuring the K8 hardware memory
scrubber via the 'mcX' sysfs directory. There should be some
fallback to a generic scrubber implemented in software if the
hardware does not support scrubbing.
Or .. the scrubbing sysfs entry should not be visible at all.
- Only works with SDRAM, not cache,
The K8 can scrub cache and l2cache also - but I think this is
not so useful as the cache is busy all the time (one hopes).
One would also expect that cache scrubbing requires hardware
support.
- Error Handling,
I would like that errors are returned to the user in
"terms of file system".
- Presentation,
I chose Bandwidth in Bytes/Second as a representation of
the scrubbing rate for the following reasons:
I like that the sysfs entries are sort-of textual, related
to something that makes sense instead of magical values
that must be looked up.
"My People" wants "% main memory scrubbed per hour" others
prefer "% memory bandwidth used" as representation, "bandwith
used" makes it easy to calculate both versions in one-liner
scripts.
If one later wants to scrub cache, the scaling becomes wierd
for K8 changing from "blocks of 64 byte memory" to "blocks of
64 cache lines" to "blocks of 64 bit". Using "bandwidth used"
makes sense in all three cases, (I.M.O. anyway ;-).
- Discovery,
There is no way to discover the possible settings and what
they do without reading the code and the documentation.
*I* do not know how to make that work in a practical way.
- Bugs(??),
other tools can set invalid values in the memory scrub
control register, those will read back as '-1', requiring
the user to reset the scrub rate. This is how *I* think it
should be.
- Afflicting other areas of code,
I made changes to edac_mc.c and edac_mc.h which will show up
globally - this is not nice, it would be better that the
memory scrubbing fuctionality and interface could be entirely
contained within the memory controller it applies to.
Frithiof Jensen
edac_mc.c and its .h file is a CORE helper module for EDAC
driver modules. This provides the abstraction for device specific
drivers. It is fine to modify this CORE to provide help for
new features of the the drivers
doug thompson
Signed-off-by: Frithiof Jensen <[email protected]>
Signed-off-by: doug thompson <[email protected]>
Documentation/drivers/edac/edac.txt | 16 +++++++++-
drivers/edac/edac_mc.c | 57
++++++++++++++++++++++++++++++++++++
drivers/edac/edac_mc.h | 12 +++++++
3 files changed, 84 insertions(+), 1 deletion(-)
Index: linux-2.6.19/drivers/edac/edac_mc.c
===================================================================
--- linux-2.6.19.orig/drivers/edac/edac_mc.c
+++ linux-2.6.19/drivers/edac/edac_mc.c
@@ -926,6 +926,59 @@ static ssize_t mci_reset_counters_store(
return count;
}
+/* memory scrubbing */
+static ssize_t mci_sdram_scrub_rate_store(struct mem_ctl_info *mci,
+ const char *data, size_t count)
+{
+ u32 bandwidth = -1;
+
+ if (mci->set_sdram_scrub_rate) {
+
+ memctrl_int_store(&bandwidth, data, count);
+
+ if (!(*mci->set_sdram_scrub_rate)(mci, &bandwidth)) {
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "Scrub rate set successfully, applied: %d\n",
+ bandwidth);
+ } else {
+ /* FIXME: error codes maybe? */
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "Scrub rate set FAILED, could not apply: %d\n",
+ bandwidth);
+ }
+
+ } else {
+ /* FIXME: produce "not implemented" ERROR for user-side. */
+ edac_printk(KERN_WARNING, EDAC_MC,
+ "Memory scrubbing 'set'control is not implemented!\n");
+ }
+ return count;
+}
+
+static ssize_t mci_sdram_scrub_rate_show(struct mem_ctl_info *mci,
char *data)
+{
+ u32 bandwidth = -1;
+
+ if (mci->get_sdram_scrub_rate) {
+ if (!(*mci->get_sdram_scrub_rate)(mci, &bandwidth)) {
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "Scrub rate successfully, fetched: %d\n",
+ bandwidth);
+ } else {
+ /* FIXME: error codes maybe? */
+ edac_printk(KERN_DEBUG, EDAC_MC,
+ "Scrub rate fetch FAILED, got: %d\n",
+ bandwidth);
+ }
+
+ } else {
+ /* FIXME: produce "not implemented" ERROR for user-side. */
+ edac_printk(KERN_WARNING, EDAC_MC,
+ "Memory scrubbing 'get' control is not implemented!\n");
+ }
+ return sprintf(data,"%d\n", bandwidth);
+}
+
/* default attribute files for the MCI object */
static ssize_t mci_ue_count_show(struct mem_ctl_info *mci, char *data)
{
@@ -1032,6 +1085,9 @@ MCIDEV_ATTR(ce_noinfo_count,S_IRUGO,mci_
MCIDEV_ATTR(ue_count,S_IRUGO,mci_ue_count_show,NULL);
MCIDEV_ATTR(ce_count,S_IRUGO,mci_ce_count_show,NULL);
+/* memory scrubber attribute file */
+MCIDEV_ATTR(sdram_scrub_rate,S_IRUGO|S_IWUSR,mci_sdram_scrub_rate_show,mci_sdram_scrub_rate_store);
+
static struct mcidev_attribute *mci_attr[] = {
&mci_attr_reset_counters,
&mci_attr_mc_name,
@@ -1041,6 +1097,7 @@ static struct mcidev_attribute *mci_attr
&mci_attr_ce_noinfo_count,
&mci_attr_ue_count,
&mci_attr_ce_count,
+ &mci_attr_sdram_scrub_rate,
NULL
};
Index: linux-2.6.19/drivers/edac/edac_mc.h
===================================================================
--- linux-2.6.19.orig/drivers/edac/edac_mc.h
+++ linux-2.6.19/drivers/edac/edac_mc.h
@@ -315,6 +315,18 @@ struct mem_ctl_info {
unsigned long scrub_cap; /* chipset scrub capabilities */
enum scrub_type scrub_mode; /* current scrub mode */
+ /* Translates sdram memory scrub rate given in bytes/sec to the
+ internal representation and configures whatever else needs
+ to be configured.
+ */
+ int (*set_sdram_scrub_rate) (struct mem_ctl_info *mci, u32 *bw);
+
+ /* Get the current sdram memory scrub rate from the internal
+ representation and converts it to the closest matching
+ bandwith in bytes/sec.
+ */
+ int (*get_sdram_scrub_rate) (struct mem_ctl_info *mci, u32 *bw);
+
/* pointer to edac checking routine */
void (*edac_check) (struct mem_ctl_info * mci);
/*
Index: linux-2.6.19/Documentation/drivers/edac/edac.txt
===================================================================
--- linux-2.6.19.orig/Documentation/drivers/edac/edac.txt
+++ linux-2.6.19/Documentation/drivers/edac/edac.txt
@@ -339,7 +339,21 @@ Device Symlink:
'device'
- Symlink to the memory controller device
+ Symlink to the memory controller device.
+
+Sdram memory scrubbing rate:
+
+ 'sdram_scrub_rate'
+
+ Read/Write attribute file that controls memory scrubbing. The
scrubbing
+ rate is set by writing a minimum bandwith in bytes/sec to the
attribute
+ file. The rate will be translated to an internal value that gives at
+ least the specified rate.
+
+ Reading the file will return the actual scrubbing rate employed.
+
+ If configuration fails or memory scrubbing is not implemented, the
value
+ of the attribute file will be -1.
"If you think Education is expensive, just try Ignorance"
"Don't tell people HOW to do things, tell them WHAT you
want and they will surprise you with their ingenuity."
Gen George Patton
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
