Date: Tue, 22 Jan 2019 15:02:09 +0530 From: shreyank amartya <shreyankfbsd@gmail.com> To: freebsd-hackers@freebsd.org Cc: freebsd-drivers@freebsd.org Subject: PCIe device performance Message-ID: <CAD9jf8DZpr7tSuPAVw2dSc3a0qufm3HVaqvvKoNoVu6MuO1qcw@mail.gmail.com>
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Hi, I have a PCIe device BAR mapped to a particular region in KVA. I use memcpy to write into that region and measure the transfer rate. Recently, I was able to increase the transfer rate by setting the memory attribute of the BAR mapped region to VM_MEMATTR_WRITE_COMBINING. However, the transfer rate fluctuates wildly and I cannot get a deterministic value. What could be the cause for this? Thanks Shreyank Amartya
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