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20f8814cd3
Measure the total deferred time (from the time we decide to defer until we try again) for busdma_load requests. On systems that don't ever defer, there is no performnce change. Add new sysctl hw.busdma.zoneX.total_deferred_time to report this (in microseconds). Normally, deferrals don't happen in modern hardware... Except there's a lot of buggy hardware that can't cope with memory > 4GB or that can't cross a 4GB boundary (or even more restrictive values), necessitating bouncing. This will measure the effect on the I/Os of this deferral. Sponsored by: Netflix Reviewed by: gallatin, mav Differential Revision: https://reviews.freebsd.org/D42550 |
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acpica | ||
bios | ||
conf | ||
cpufreq | ||
include | ||
iommu | ||
isa | ||
linux | ||
pci | ||
x86 | ||
xen |