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[ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/includes/bbcode.php on line 112: preg_replace(): The /e modifier is no longer supported, use preg_replace_callback instead [phpBB Debug] PHP Warning: in file [ROOT]/feed.php on line 173: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3823) [phpBB Debug] PHP Warning: in file [ROOT]/feed.php on line 174: Cannot modify header information - headers already sent by (output started at [ROOT]/includes/functions.php:3823) Parallella CommunitySupercomputing for Everyone2014-07-10T13:30:29+00:00https://parallella.org/forums/feed.php?f=47&t=14492014-07-10T13:30:29+00:002014-07-10T13:30:29+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9160#p9160<![CDATA[Re: FFT sample for 2^20 elements]]> I don't have any use for a large fft to start with.
]]>2014-07-10T11:46:48+00:002014-07-10T11:46:48+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9158#p9158<![CDATA[Re: FFT sample for 2^20 elements]]> Tim
Statistics: Posted by timpart — Thu Jul 10, 2014 11:46 am
]]>2014-07-10T08:41:32+00:002014-07-10T08:41:32+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9156#p9156<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by notzed — Thu Jul 10, 2014 8:41 am
]]>2014-07-07T14:53:43+00:002014-07-07T14:53:43+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9107#p9107<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by notzed — Mon Jul 07, 2014 2:53 pm
]]>2014-07-07T11:59:46+00:002014-07-07T11:59:46+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9103#p9103<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by timpart — Mon Jul 07, 2014 11:59 am
]]>2014-07-07T09:01:43+00:002014-07-07T09:01:43+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9101#p9101<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by notzed — Mon Jul 07, 2014 9:01 am
]]>2014-07-06T14:48:44+00:002014-07-06T14:48:44+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9084#p9084<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by Bikeman — Sun Jul 06, 2014 2:48 pm
]]>2014-07-06T13:58:30+00:002014-07-06T13:58:30+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9082#p9082<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by notzed — Sun Jul 06, 2014 1:58 pm
]]>2014-07-05T09:57:32+00:002014-07-05T09:57:32+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9051#p9051<![CDATA[Re: FFT sample for 2^20 elements]]>Statistics: Posted by Bikeman — Sat Jul 05, 2014 9:57 am
]]>2014-07-05T08:44:25+00:002014-07-05T08:44:25+00:00https://parallella.org/forums/viewtopic.php?t=1449&p=9047#p9047<![CDATA[FFT sample for 2^20 elements]]> The sample implements a forward complex fft for 2^20 elements by breaking it into steps of 1024 which fits into LDS and allows the fft to be calculated using two passes through external memory. It needs to operate out-of-place.
Even with synchronous dma transfers, calculating the twiddle factors on-core, and a not particularly sophisticated radix-4 inner loop, memory bandwidth is the limiting factor beyond 4 cores being active (it's already limiting beyond 2).
Given memory is the bottleneck, the only thing I can think of to get more performance is to serialise (and group where possible) the dma writes to get a bit more bandwidth. Unless i'm missing something and there's a way to get away with a single main memory pass.
knew i should've left it till tomorrow. the fft stuff in 0.3 is broken as i checked in some experiments, 0.3.1 coming soon.
Statistics: Posted by notzed — Sat Jul 05, 2014 8:44 am