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Subject: Re: [OMPI devel] FDR: bad patch? (was: 1.6rc3 is out)
From: Ludovic.Hablot_at_[hidden]
Date: 2012-05-09 11:33:14


Well, looking at the libverbs sources, it seems that there is a patch for devinfo (cf below).

Thus, the correct speeds, according to the libibverbs patch. And, if I understand well, they must be 
multiplied by the coding ratio to get the real link speed.

I joined another patch. I don't know if we should remove the case 4 and fall through case 8 or just keep it as I do.

Regards,

Ludovic

libibverbs/fixes/add_support_for_extended_speends.patch

[PATCH]libibverbs: Add support for extended speeds

8:  FDR-10 is a proprietary link speed which is 10.3125 Gbps at 64/66
    encoding rather than 8b10b encoding.
16: FDR - 14.0625 Gbps
32: EDR - 25.78125 Gbps

+--- a/examples/devinfo.c
++++ b/examples/devinfo.c
+@@ -139,7 +139,12 @@ static const char *speed_str(uint8_t speed)
+ switch (speed) {
+ case 1:  return "2.5 Gbps";
+ case 2:  return "5.0 Gbps";
+- case 4:  return "10.0 Gbps";
++
++ case 4:  /* fall through */
++ case 8:  return "10.0 Gbps";
++
++ case 16: return "14.0 Gbps";
++ case 32: return "25.0 Gbps";
+ default: return "invalid speed";
+ }
+ }

-----devel-bounces_at_[hidden] a écrit : -----
A : devel_at_[hidden]
De : Peter Kjellström
Envoyé par : devel-bounces_at_[hidden]
Date : 09/05/2012 16:35
Objet : Re: [OMPI devel] FDR: bad patch? (was: 1.6rc3 is out)

On Wednesday 09 May 2012 10.20.47 Jeff Squyres wrote:
...
> I don't have any QDR or FDR equipment -- what's the typical active_width for
> QDR and FDR?
>
> QDR is 32000, so is that active_speed of 4 and active_width of 4? (8000 * 4
> = 32000)?
>
> FDR is 56000 (right?
 
Pretty much all IB is 4x to host.
 
4x QDR is 40 Gbps at link level => 8 Gbps data per link (8/10 coding)
4x FDR10 is 40 Gbps at link level => ~9.7 Gbps data per link (64/66 coding)
4x FDR is 56 Gbps at link level => ~13.5 Gbps data per link (64/66 coding)
 
/Peter
 
> I haven't kept up with IB specs since Cisco killed
> IB...), so what are its active_speed and active_width values?
 

--
-= Peter Kjellström
-= National Supercomputer Centre
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