From: Or Gerlitz <ogerlitz-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org>
To: Ido Shamai
<idos-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>,
Jack Morgenstein <jackm-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org>
Cc: linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Moni Shoua <monis-smomgflXvOZWk0Htik3J/w@public.gmane.org>,
Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Alex Rosenbaum <Alexr-smomgflXvOZWk0Htik3J/w@public.gmane.org>
Subject: Re: rdma_lat whos
Date: Wed, 24 Nov 2010 17:00:51 +0200 [thread overview]
Message-ID: <4CED28A3.9070907@Voltaire.com> (raw)
In-Reply-To: <4CE50190.3080707-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
Ido Shamai wrote:
> I will check the issue now.
Thinking a little further on this and talking with some colleagues, a question was made,
whether the issue can be related to IB credits/starvation and/or protocol/interoperability
with switches.
In an attempt to eliminate that, I repeated the test, this time in a loopback manner, e.g used ib_send_lat once with mtu=256 and once with mtu=2048 with both client/server running on the same node/hca - same result, the mtu=256 produces much better latency for large messages, e.g 1k and onward, for example for msg size=8k the latency is ~7us with mtu=256 and ~9us with mtu=2k
I recalled that on the 2nd generation HCA (tavor), if mtu=2048 is used, the bandwidth is severely damaged (hence the ofed tavor quirk and friends) can this problem which I see on the 4th generation HCA, be somehow related?
Or.
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next prev parent reply other threads:[~2010-11-24 15:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-17 10:54 rdma_lat whos Or Gerlitz
[not found] ` <4CE3B455.4080003-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org>
2010-11-17 11:30 ` Or Gerlitz
[not found] ` <4CE3BCE3.7090107-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org>
2010-11-18 10:36 ` Ido Shamai
[not found] ` <4CE50190.3080707-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2010-11-18 11:44 ` Or Gerlitz
[not found] ` <4CE511A8.9010400-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org>
2010-11-18 11:49 ` Vladimir Sokolovsky
[not found] ` <4CE512B7.9080608-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
2010-11-18 12:38 ` Or Gerlitz
2010-11-24 15:00 ` Or Gerlitz [this message]
2010-12-09 10:33 ` Or Gerlitz
[not found] ` <4D00B066.80807-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org>
2010-12-09 10:39 ` Or Gerlitz
[not found] ` <4D00B1C4.3040804-hKgKHo2Ms0FWk0Htik3J/w@public.gmane.org>
2010-12-09 17:28 ` Jason Gunthorpe
2010-12-09 12:20 ` Or Gerlitz
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