Messages in this thread | | | Date | Wed, 6 Jul 2016 07:04:31 +0200 | From | Willy Tarreau <> | Subject | Re: [PATCH net] net: mvneta: set real interrupt per packet for tx_done |
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Hi,
On Wed, Jul 06, 2016 at 04:18:58AM +0200, Marcin Wojtas wrote: > From: Dmitri Epshtein <dima@marvell.com> > > Commit aebea2ba0f74 ("net: mvneta: fix Tx interrupt delay") intended to > set coalescing threshold to a value guaranteeing interrupt generation > per each sent packet, so that buffers can be released with no delay. > > In fact setting threshold to '1' was wrong, because it causes interrupt > every two packets. According to the documentation a reason behind it is > following - interrupt occurs once sent buffers counter reaches a value, > which is higher than one specified in MVNETA_TXQ_SIZE_REG(q). This > behavior was confirmed during tests. Also when testing the SoC working > as a NAS device, better performance was observed with int-per-packet, > as it strongly depends on the fact that all transmitted packets are > released immediately. > > This commit enables NETA controller work in interrupt per sent packet mode > by setting coalescing threshold to 0.
We had a discussion about this in January 2015 and I thought I sent a patch to change it but I can't find it, so I think it was only proposed to some users for testing. I also remember that on more recent kernels by then (>=3.13) we observed a slightly better performance with this value set to zero.
Acked-by: Willy Tarreau <w@1wt.eu>
Willy
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