[SPARC64]: Fix bad performance side effect of strbuf timeout changes.

The recent change to add a timeout to strbuf flushing had
a negative performance impact.  The udelay()'s are too long,
and they were done in the wrong order wrt. the register read
checks.  Fix both, and things are happy again.

There are more possible improvements in this area.  In fact,
PCI streaming buffer flushing seems to be part of the bottleneck
in network receive performance on my SunBlade1000 box.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc64/kernel/pci_iommu.c b/arch/sparc64/kernel/pci_iommu.c
index f009b1b455010e8b425031976caf7f3a9a1ce0d4..33ca56c90da2637a6e233535239d74131c1b5455 100644 (file)
--- a/arch/sparc64/kernel/pci_iommu.c
+++ b/arch/sparc64/kernel/pci_iommu.c
@@ -392,14 +392,16 @@ static void pci_strbuf_flush(struct pci_strbuf *strbuf, struct pci_iommu *iommu,
                flushreg = strbuf->strbuf_ctxflush;
                matchreg = PCI_STC_CTXMATCH_ADDR(strbuf, ctx);
 
-               limit = 10000;
-               do {
-                       pci_iommu_write(flushreg, ctx);
-                       udelay(10);
+               limit = 100000;
+               pci_iommu_write(flushreg, ctx);
+               for(;;) {
+                       if (((long)pci_iommu_read(matchreg)) >= 0L)
+                               break;
                        limit--;
                        if (!limit)
                                break;
-               } while(((long)pci_iommu_read(matchreg)) < 0L);
+                       udelay(1);
+               }
                if (!limit)
                        printk(KERN_WARNING "pci_strbuf_flush: ctx flush "
                               "timeout vaddr[%08x] ctx[%lx]\n",
@@ -414,12 +416,12 @@ static void pci_strbuf_flush(struct pci_strbuf *strbuf, struct pci_iommu *iommu,
        pci_iommu_write(strbuf->strbuf_fsync, strbuf->strbuf_flushflag_pa);
        (void) pci_iommu_read(iommu->write_complete_reg);
 
-       limit = 10000;
+       limit = 100000;
        while (!PCI_STC_FLUSHFLAG_SET(strbuf)) {
                limit--;
                if (!limit)
                        break;
-               udelay(10);
+               udelay(1);
                membar("#LoadLoad");
        }
        if (!limit)

diff --git a/arch/sparc64/kernel/sbus.c b/arch/sparc64/kernel/sbus.c
index d3eca98e1fe741e3326ed86671dae1ad132de706..76ea6455433f1a7aa89005190b4fe60d56d3aea3 100644 (file)
--- a/arch/sparc64/kernel/sbus.c
+++ b/arch/sparc64/kernel/sbus.c
@@ -133,12 +133,12 @@ static void sbus_strbuf_flush(struct sbus_iommu *iommu, u32 base, unsigned long
                   iommu->strbuf_regs + STRBUF_FSYNC);
        upa_readq(iommu->sbus_control_reg);
 
-       limit = 10000;
+       limit = 100000;
        while (iommu->strbuf_flushflag == 0UL) {
                limit--;
                if (!limit)
                        break;
-               udelay(10);
+               udelay(1);
                membar("#LoadLoad");
        }
        if (!limit)