Date: Thu, 25 Sep 2014 16:08:10 +0400 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Ryan Stone <rysto32@gmail.com> Cc: freebsd-net <freebsd-net@freebsd.org> Subject: Re: [PATCH] Convert ixl(4) and ixlv(4) to ifcounters, and fix some counter bugs Message-ID: <20140925120810.GA884@FreeBSD.org> In-Reply-To: <CAFMmRNyn0Kjr30Ew%2B8YRRvT-tMFH6WdprAAyJieLz_ABDNK8%2BA@mail.gmail.com> References: <CAFMmRNyn0Kjr30Ew%2B8YRRvT-tMFH6WdprAAyJieLz_ABDNK8%2BA@mail.gmail.com>
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On Tue, Sep 23, 2014 at 07:18:51PM -0400, Ryan Stone wrote: R> The patch below converts the ixl(4) and ixlv(4) drivers to use the new R> ifcounter interface. I've hidden the interface behind some macros to R> ensure that the driver continues to compile for FreeBSD 10 and R> earlier. The result of the macros is that the ifcounter R> implementation is somewhat clunkier than I would have liked, but I R> preferred to try and share as much code between the legacy counter R> implementation and the ifcounter implementation. R> R> I have tested the ixl driver with head. I have only compile-tested it R> for stable/10. R> R> This patch also fixes some counter bugs: R> R> - Ensure that tx discards are reported R> - There are actually two types of rx discard counters in the hardware. R> Currently the driver is only reporting discards from one of the two R> counters, so I fixed that R> - The ipackets and opackets counters were being unnecessarily R> incremented in the rx and tx paths. This was racy, unnecessary (the R> counters also get explicitly set based on the values in HW counters) R> and very bad for performance -- the cacheline contained the counters R> was constantly bouncing between CPUs. I saw this even with only one R> queue active, probably due to false sharing with some other field in R> the ifnet struct. R> R> https://people.freebsd.org/~rstone/patches/ixl/0005-Convert-ixl-and-ixlv-drivers-to-use-new-ifcounter-in.patch Thanks, Ryan! I'd suggest to use check against __FreeBSD_version >= 1100036. Can you please commit this? Navdeep promised to do cxgbe(4), Alexander is working on ixgbe. After that we can go forward with making counters in struct ifnet non-racy and cheap counter(9). -- Totus tuus, Glebius.
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