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authorDave Olson <dave.olson@qlogic.com>2007-06-01 13:01:47 -0700
committerRoland Dreier <rolandd@cisco.com>2007-10-09 20:20:15 -0700
commit9bec3992312b8bb3aee71bd3b57d106a0a649479 (patch)
tree7ef51e3e5eb5cd84682e9d2742679f86b9227fbb
parent4ee97180ac76deb5a715ac45b7d7516e6ee82ae7 (diff)
IB/ipath: Verify host bus bandwidth to chip will not limit performance
There have been a number of issues where host bandwidth via HT or PCIe to the InfiniPath chip has been limited in some fashion (BIOS, configuration, etc.), resulting in user confusion. This check gives a clear warning that something is wrong and needs to be resolved. Signed-off-by: Dave Olson <dave.olson@qlogic.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
-rw-r--r--drivers/infiniband/hw/ipath/ipath_driver.c86
1 files changed, 86 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index 6ccba365a24..5248f57fe19 100644
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -34,6 +34,7 @@
#include <linux/spinlock.h>
#include <linux/idr.h>
#include <linux/pci.h>
+#include <linux/io.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
@@ -280,6 +281,89 @@ void __attribute__((weak)) ipath_disable_wc(struct ipath_devdata *dd)
{
}
+/*
+ * Perform a PIO buffer bandwidth write test, to verify proper system
+ * configuration. Even when all the setup calls work, occasionally
+ * BIOS or other issues can prevent write combining from working, or
+ * can cause other bandwidth problems to the chip.
+ *
+ * This test simply writes the same buffer over and over again, and
+ * measures close to the peak bandwidth to the chip (not testing
+ * data bandwidth to the wire). On chips that use an address-based
+ * trigger to send packets to the wire, this is easy. On chips that
+ * use a count to trigger, we want to make sure that the packet doesn't
+ * go out on the wire, or trigger flow control checks.
+ */
+static void ipath_verify_pioperf(struct ipath_devdata *dd)
+{
+ u32 pbnum, cnt, lcnt;
+ u32 __iomem *piobuf;
+ u32 *addr;
+ u64 msecs, emsecs;
+
+ piobuf = ipath_getpiobuf(dd, &pbnum);
+ if (!piobuf) {
+ dev_info(&dd->pcidev->dev,
+ "No PIObufs for checking perf, skipping\n");
+ return;
+ }
+
+ /*
+ * Enough to give us a reasonable test, less than piobuf size, and
+ * likely multiple of store buffer length.
+ */
+ cnt = 1024;
+
+ addr = vmalloc(cnt);
+ if (!addr) {
+ dev_info(&dd->pcidev->dev,
+ "Couldn't get memory for checking PIO perf,"
+ " skipping\n");
+ goto done;
+ }
+
+ preempt_disable(); /* we want reasonably accurate elapsed time */
+ msecs = 1 + jiffies_to_msecs(jiffies);
+ for (lcnt = 0; lcnt < 10000U; lcnt++) {
+ /* wait until we cross msec boundary */
+ if (jiffies_to_msecs(jiffies) >= msecs)
+ break;
+ udelay(1);
+ }
+
+ writeq(0, piobuf); /* length 0, no dwords actually sent */
+ ipath_flush_wc();
+
+ /*
+ * this is only roughly accurate, since even with preempt we
+ * still take interrupts that could take a while. Running for
+ * >= 5 msec seems to get us "close enough" to accurate values
+ */
+ msecs = jiffies_to_msecs(jiffies);
+ for (emsecs = lcnt = 0; emsecs <= 5UL; lcnt++) {
+ __iowrite32_copy(piobuf + 64, addr, cnt >> 2);
+ emsecs = jiffies_to_msecs(jiffies) - msecs;
+ }
+
+ /* 1 GiB/sec, slightly over IB SDR line rate */
+ if (lcnt < (emsecs * 1024U))
+ ipath_dev_err(dd,
+ "Performance problem: bandwidth to PIO buffers is "
+ "only %u MiB/sec\n",
+ lcnt / (u32) emsecs);
+ else
+ ipath_dbg("PIO buffer bandwidth %u MiB/sec is OK\n",
+ lcnt / (u32) emsecs);
+
+ preempt_enable();
+
+ vfree(addr);
+
+done:
+ /* disarm piobuf, so it's available again */
+ ipath_disarm_piobufs(dd, pbnum, 1);
+}
+
static int __devinit ipath_init_one(struct pci_dev *pdev,
const struct pci_device_id *ent)
{
@@ -515,6 +599,8 @@ static int __devinit ipath_init_one(struct pci_dev *pdev,
ret = 0;
}
+ ipath_verify_pioperf(dd);
+
ipath_device_create_group(&pdev->dev, dd);
ipathfs_add_device(dd);
ipath_user_add(dd);