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<DIV>Donnerstag, 31. Januar 2008, meintest Du:</DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<P><FONT face=Arial color=#0000ff size=2></FONT><BR></P>
<P><SPAN class=rvts6>SA> On Jan 30, 2008, at 6:20 PM, Gilad Shainer
wrote:</SPAN></P>
<P><BR></P>
<P><SPAN class=rvts7>>> For BW, Lx provides ~1400MB/s, EX is ~1500MB/s
and ConnectX is </SPAN></P>
<P><SPAN class=rvts7>>> ~1900MB/s</SPAN></P>
<P><SPAN class=rvts7>>> uni-directional on PCIe Gen2.</SPAN></P>
<P><BR></P>
<P><SPAN class=rvts7>>> Feel free to contact me directly for more
info.</SPAN></P>
<P><BR></P>
<P><SPAN class=rvts7>>> Gilad.</SPAN></P>
<P><BR></P>
<P><SPAN class=rvts6>SA> My god, IB bandwidths always confuse me.
:-)</SPAN></P>
<P><BR></P>
<P><SPAN class=rvts6>SA> I thought IB SDR was 10 GB/s signal rate and 8
Gb/s data rate. How do</SPAN></P>
<P><SPAN class=rvts6>SA> you squeeze ~1400 MB/s out of 8 Gb/s?</SPAN></P>
<P><BR></P>
<P>The 1400 MB/ are probably for DDR mode which is 20 GB/s signal rate and 16
GB/s data rate. </P>
<P><BR></P>
<P><SPAN class=rvts6>SA> I see you offer Lx cards in PCIe 4x and 8x. Again,
PCIe is encoded at</SPAN></P>
<P><SPAN class=rvts6>SA> 10bit/8bit so the data rate is 8 Gb/s. So the
above value is for your</SPAN></P>
<P><SPAN class=rvts6>SA> 8x cards only, no? The thread is about your 4x
cards, no?</SPAN></P>
<P><BR></P>
<P>Values are for x8 cards. </P>
<P><BR></P>
<P>I tested the x4 cards a few months ago and what i measured was: </P>
<P><BR></P>
<P>- Latency was not affected by the slower PCIe connection</P>
<P>- Bandwidth dropped to 700-750 MB/s where it is 900 to 950 with a x8 SDR
card.<SPAN class=578554417-31012008><FONT face=Arial color=#0000ff
size=2> </FONT></SPAN></P>
<P><SPAN class=578554417-31012008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </P></BLOCKQUOTE>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=578554417-31012008>Gilad: Lx is been used in PCIe x8 and x4, and in the
PCIe x8 adapters - you can find IB SDR and IB DDR. The cards mentioned in the
article are the IB SDR PCIe x4 with provide the same low latency, and the
BW is limited by the PCIe to ~750MB/s. With the recent chipsets it is little
bit higher.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=578554417-31012008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=578554417-31012008> </SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<P><BR></P>
<P>(Intel MPI Benchmarks, pingpong)</P>
<P><BR></P>
<P>It depends on your application if the lower bandwidth affects
performance.</P>
<P><BR></P>
<P>Regards,</P>
<P>Jan</P></BLOCKQUOTE>
!DSPAM:47a20d32148849691080364!
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