Date: Thu, 26 Sep 1996 20:03:01 +0200 (MET DST) From: Stefan Esser <se@zpr.uni-koeln.de> To: Kees.Koster@nym.sc.philips.com Cc: hardware@freebsd.org Subject: Re: lmbench results for AMD 5k86-P100 Message-ID: <199609261803.UAA08010@x14.mi.uni-koeln.de> In-Reply-To: <2A363AB4B4F@NLNMG01.nym.sc.philips.com> References: <2A363AB4B4F@NLNMG01.nym.sc.philips.com>
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Kees Jan Koster writes: > I did a little benchmarking on my machine, as Stefan requested (are > you on this list?). I haven't had the time to do the bytebench yet. Yes, I'm on the list ... > Maybe later. I'd appreciate it ... > Machine: Exp8661 mainboard, 512kb PB cache, 32Mb EDO, > AMD 5k86-P100 @ 100MHz (overclocking doesn't work :). Well, they'd be selling 5k86-120 chips, if it did :) > Could someone shed some light on the 'bad MHz' messages below? > It worries me a little, because I had some touble before. Unix worked > like it always has: sweet as honey, and MS-DOS kept tripping over its > feet: random hangs and crashes, missed sequences on the soundcard, > etc. According to an article in c't magazine (currently the best computer mag in Germany, INOMHO), this is due to the fact that the 5k86 uses random replacement in its primary cache. It is 4 way set-associative as that of other x86 CPUs, but twice as large (16KB) as that of the P5. There is a version of "ctcm" that has been modified for the 5k86, since they (c't mag) could not find the cache access time, else (same as lmbench :) > Both Unix and MS-DOS work, altough MS-DOS still feels kind'a fragile. I don't care for DOS, but it's a little surprising to hear, that Unix runs better (more reliable) than DOS on some hardware. But I could consider this fact as pro-AMD5K :) Since I wanted to know how the 5k86 compares to my 5x86, I performed a lmbench run on my system, too. I'm using the later 1.1 version of lmbench, which is not yet available as a port (but it is trivial, and I'll send a diff to ASAMI Satoshi). Seems that the 5x86/133 (which is rated as equivalent to the Pentium 75) is 60% of the 5k86-100 (which ought to be as fast as a P100) in those tests, were 2.1.5 and -current are not too different. (Ie.: ignore the 5x86's PIPE performance ... :) My system was not idle, but I think the results are useful anyway :) > L M B E N C H 1 . 0 S U M M A R Y > ------------------------------------ > > Processor, Processes - times in microseconds > -------------------------------------------- > Host OS Mhz Null Null Simple /bin/sh Mmap 2-proc 8-proc > Syscall Process Process Process lat ctxsw ctxsw > --------- ------------- ---- ------- ------- ------- ------- ---- ------ ------ amd5x86 FreeBSD 2.2-C 132 13 4K 19K 40K 148 15 26 > LikeEver FreeBSD 2.1.5 100 6 3.8K 14.2K 24K 123 35 44 > LikeEver. FreeBSD 2.1.5 100 6 3.9K 14.1K 26K 123 36 46 > LikeEver. FreeBSD 2.1.5 100 6 3.9K 14.0K 24K 124 36 46 > pentium Linux 1.1.54 91 3 3.3K 15.4K 49K 33 25 42 The 5k86 is FAR slower in the context-switch tests. This might be due to changes between -stable and -current, or because of wrong assumptions in the case of the 5k86. Is there a cache or TLB flush in the context switch code ? > *Local* Communication latencies in microseconds > ----------------------------------------------- > Host OS Pipe UDP RPC/ TCP RPC/ > UDP TCP > --------- ------------- ------- ------- ------- ------- ------- amd5x86 FreeBSD 2.2-C 76 353 751 460 938 > LikeEver FreeBSD 2.1.5 101 204 421 251 568 > LikeEver. FreeBSD 2.1.5 103 214 427 268 594 > LikeEver. FreeBSD 2.1.5 103 208 430 260 579 > pentium Linux 1.1.54 157 658 1030 1164 1591 Except for the pipe code, the 5k86 is a factor of 5/3 as fast ... > *Local* Communication bandwidths in megabytes/second > ---------------------------------------------------- > Host OS Pipe TCP File Mmap Bcopy Bcopy Mem Mem > reread reread (libc) (hand) read write > -------- ------------- ---- ---- ------ ------ ------ ------ ---- amd5x86 FreeBSD 2.2-C 30 7 14 25 16 15 34 41 > LikeEver FreeBSD 2.1.5 14 9.6 23.1 58.6 29 28 81 42 > LikeEver FreeBSD 2.1.5 14 9.6 23.1 57.7 29 28 81 42 > LikeEver FreeBSD 2.1.5 14 9.7 23.1 58.4 29 28 81 42 > pentium Linux 1.1.54 13 2.4 9.8 4.7 18 18 48 32 The 5k86 is special in that its memory read performance is much better (by a factor of 2) than its write performance. Not sure why, but this may also be caused by the motherboards characteristics. (What chip-set is that, BTW ?) > Memory latencies in nanoseconds > (WARNING - may not be correct, check graphs) > -------------------------------------------- > Host OS Mhz L1 $ L2 $ Main mem TLB Guesses > --------- ------------- --- ---- ---- -------- --- ------- amd5x86 FreeBSD 2.2-C 131 9 147 341 > LikeEver FreeBSD 2.1.5 100 - - - - Bad mhz? > LikeEver. FreeBSD 2.1.5 100 - - - - Bad mhz? > LikeEver. FreeBSD 2.1.5 100 - - - - Bad mhz? > pentium Linux 1.1.54 90 11 294 439 1254 Hmm, as you can see, a 486 class CPU under FreeBSD offers better memory and cache latencies than a Pentium under Linux :) :) (And even with twice the first level cache size ...) LMBENCH for sure is not the best CPU benchmark, but it seems the 5k86 is at least comparable to a P5-100, and seems to be a cost effective alternative for a server that does not need to offer peak performance values ... Thanks for posting the interesting 5k86 results ! STefan
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