* ib_read_lat question
@ 2013-02-21 17:50 Steve Wise
[not found] ` <51265E60.1070609-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Steve Wise @ 2013-02-21 17:50 UTC (permalink / raw)
To: idos-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Hey Ido,
ib_read_lat displays RTT latency, while the other lat programs display
RTT/2. Is this intended? Or is read_lat.c/print_report() missing a
divide-by-two?
Thanks,
Steve.
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* RE: ib_read_lat question
[not found] ` <51265E60.1070609-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
@ 2013-02-21 18:27 ` Hefty, Sean
[not found] ` <1828884A29C6694DAF28B7E6B8A823736F35235F-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Hefty, Sean @ 2013-02-21 18:27 UTC (permalink / raw)
To: Steve Wise,
idos-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> ib_read_lat displays RTT latency, while the other lat programs display
> RTT/2. Is this intended? Or is read_lat.c/print_report() missing a
> divide-by-two?
The tests should measure how long it takes the data to reach the destination. For writes/sends, that would be RTT/2. For reads, the destination is local, so you should want RTT.
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* Re: ib_read_lat question
[not found] ` <1828884A29C6694DAF28B7E6B8A823736F35235F-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
@ 2013-02-21 18:34 ` Steve Wise
[not found] ` <512668BF.4030908-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Steve Wise @ 2013-02-21 18:34 UTC (permalink / raw)
To: Hefty, Sean
Cc: idos-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Troy Leedberg
On 2/21/2013 12:27 PM, Hefty, Sean wrote:
>> ib_read_lat displays RTT latency, while the other lat programs display
>> RTT/2. Is this intended? Or is read_lat.c/print_report() missing a
>> divide-by-two?
> The tests should measure how long it takes the data to reach the destination. For writes/sends, that would be RTT/2. For reads, the destination is local, so you should want RTT.
Guess that makes sense.
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* Re: ib_read_lat question
[not found] ` <512668BF.4030908-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
@ 2013-02-27 8:46 ` Ido Shamai
0 siblings, 0 replies; 4+ messages in thread
From: Ido Shamai @ 2013-02-27 8:46 UTC (permalink / raw)
To: Steve Wise
Cc: Hefty, Sean, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Troy Leedberg
On 2/21/2013 8:34 PM, Steve Wise wrote:
> On 2/21/2013 12:27 PM, Hefty, Sean wrote:
>>> ib_read_lat displays RTT latency, while the other lat programs display
>>> RTT/2. Is this intended? Or is read_lat.c/print_report() missing a
>>> divide-by-two?
>> The tests should measure how long it takes the data to reach the
>> destination. For writes/sends, that would be RTT/2. For reads, the
>> destination is local, so you should want RTT.
>
> Guess that makes sense.
>
Yes, to me too.
Thanks Sean
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2013-02-21 17:50 ib_read_lat question Steve Wise
[not found] ` <51265E60.1070609-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
2013-02-21 18:27 ` Hefty, Sean
[not found] ` <1828884A29C6694DAF28B7E6B8A823736F35235F-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2013-02-21 18:34 ` Steve Wise
[not found] ` <512668BF.4030908-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
2013-02-27 8:46 ` Ido Shamai
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