Messages in this thread | | | Date | Sun, 22 Feb 1998 09:44:37 -0800 (PST) | From | Trevor Johnson <> | Subject | Re: Can Kernel Compression Code make Sense? |
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> Hm... I'm able to write with a spedd of about 3 MB/sec to my HD > with only a few cpucycles lost (you know, It's the think called SCSI :)) > Compressing my cache hast to be at least that fast but will always > take much more cpucycles... that's why I think it will be always a lost > of performance...
# hdparm -t -T /dev/hdc
/dev/hdc: Timing buffer-cache reads: 32 MB in 10.30 seconds = 3.11 MB/sec Timing buffered disk reads: 16 MB in 4.89 seconds = 3.27 MB/sec Hmm.. suspicious results: probably not enough free memory for a proper test. % /usr/bin/time zcat linux-2.1.87.tar.gz>/dev/null 12.99user 2.46system 0:16.20elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (2666major+34minor)pagefaults 0swaps % /usr/bin/time cat linux-2.1.87.tar>/dev/null 0.09user 11.36system 0:14.31elapsed 79%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (10859major+12minor)pagefaults 0swaps % ls -l linux-2.1.87.tar* -rw-r--r-- 1 root root 44165120 Feb 22 09:03 linux-2.1.87.tar -rw-r--r-- 1 root root 10519265 Feb 17 01:58 linux-2.1.87.tar.gz
In this example it's a little slower with compression, but nonetheless I still use it. This isn't (just) because I'm crazy, but because more data (in this example, 4.2 times as much) will fit on the hard drive when compressed, and the hard drive is limited in size. Things that don't fit could go to several places, all much slower:
SCSI hard drive, about 700 kB/s CD-RW, 345 kB/s DAT tape, 172 kB/s Ethernet, 60 kB/s floppy, 36 kB/s modem, 2.8 kB/s on a good day ___ Trevor Johnson
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