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Message-ID: <4C8953D3.9060204@hp.com> Date: Thu, 09 Sep 2010 14:38:27 -0700 From: Rick Jones <rick.jones2@...com> To: David Miller <davem@...emloft.net> CC: ole@....pl, eric.dumazet@...il.com, netdev@...r.kernel.org, eilong@...adcom.com Subject: Re: [RFC] bnx2x: Insane RX rings David Miller wrote: > From: Krzysztof Olędzki <ole@....pl> > Date: Thu, 09 Sep 2010 23:21:01 +0200 > > >>On 2010-09-09 22:45, Eric Dumazet wrote: >> >>>Problem is : With 16 RX queues per device , thats 4078*16*2Kbytes per >>>ethernet port. >>> >>>Total : >>> >>>skbuff_head_cache 130747 131025 256 15 1 : tunables 120 60 8 : >>>slabdata 8735 8735 40 >>>size-2048 130866 130888 2048 2 1 : tunables 24 12 8 : slabdata 65444 >>>65444 28 >>> >>>Thats about 300 Mbytes of memory, just in case some network trafic >>>will occur. >>> >>>Lets do something about that ? >> >>Yep, it is ~8MB per queue, not so much alone, but a lot together. For >>this reason I use something like bnx2.num_queues=2 on servers where I >>don't need much CPU power for network workload. > > > I think simply that the RX queue size should be scaled by the number > of queues we have. > > If people want enormous RX ring sizes even when there are many queues, > they can use ethtool to get that. > > Taking up 130MB of memory per-card, just for RX packet buffers, is > certainly over the top. It gets even better if one consideres JumboFrames... that said, I've had customer contacts (indirect) where they were quite keep to have a ring size of at least 2048 packets - I never could get it confirmed, but I suspect they had applications/systems that might "go out to lunch" for long-enough periods of time they wanted that degree of FIFO. Doesn't necessarily change "what should be the defaults" much but there it is. rick jones -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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