[PATCH] x86_64: Use cpu_relax in poll loop in GART IOMMU
The code waits for the GART to clear the TLB flush bit. Use cpu_relax in this time to allow hypervisors to yield the CPU in this time. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -148,9 +148,12 @@ static void flush_gart(struct device *dev)
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if (!northbridges[i])
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if (!northbridges[i])
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continue;
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continue;
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/* Make sure the hardware actually executed the flush. */
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/* Make sure the hardware actually executed the flush. */
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do {
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for (;;) {
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pci_read_config_dword(northbridges[i], 0x9c, &w);
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pci_read_config_dword(northbridges[i], 0x9c, &w);
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} while (w & 1);
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if (!(w & 1))
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break;
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cpu_relax();
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}
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}
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}
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if (!flushed)
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if (!flushed)
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printk("nothing to flush?\n");
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printk("nothing to flush?\n");
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