Author: mav
Date: Sat Sep 6 19:43:48 2014
New Revision: 271207
URL: http://svnweb.freebsd.org/changeset/base/271207
Log:
Save one register read (AHCI_IS) for AHCI controllers with only one port.
For controllers with only one port (like PCIe or M.2 SSDs) interrupt can
come from only one source, and skipping read saves few percents of CPU time.
MFC after: 1 month
H/W donated by: I/O Switch
Modified:
head/sys/dev/ahci/ahci.c
Modified: head/sys/dev/ahci/ahci.c
==============================================================================
--- head/sys/dev/ahci/ahci.c Sat Sep 6 19:39:12 2014 (r271206)
+++ head/sys/dev/ahci/ahci.c Sat Sep 6 19:43:48 2014 (r271207)
@@ -359,7 +359,9 @@ ahci_setup_interrupt(device_t dev)
for (i = 0; i < ctlr->numirqs; i++) {
ctlr->irqs[i].ctlr = ctlr;
ctlr->irqs[i].r_irq_rid = i + (ctlr->msi ? 1 : 0);
- if (ctlr->numirqs == 1 || i >= ctlr->channels ||
+ if (ctlr->channels == 1 && !ctlr->ccc)
+ ctlr->irqs[i].mode = AHCI_IRQ_MODE_ONE;
+ else if (ctlr->numirqs == 1 || i >= ctlr->channels ||
(ctlr->ccc && i == ctlr->cccv))
ctlr->irqs[i].mode = AHCI_IRQ_MODE_ALL;
else if (i == ctlr->numirqs - 1)
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