Date: Sun, 31 Jan 1999 11:33:15 +0100 From: Andre Albsmeier <andre.albsmeier@mchp.siemens.de> To: freebsd-questions@FreeBSD.ORG Subject: How idle is idletime scheduling priority really ? Message-ID: <19990131113315.A6351@internal>
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I wonder what effect has idle priority on system activities, I fear not much. Let's assume the following scenario: Two hosts (2.2.8-STABLE) connected via 100MBit with a 35MB file for testing via ftp. Small test shell script: #!/bin/sh while true; do true done 1. Both hosts idle: Speed 10.17 MB/s ftp> get aa local: aa remote: aa 227 Entering Passive Mode (192,168,18,2,156,75) 150 Opening BINARY mode data connection for 'aa' (36746099 bytes). 100% |**********************************************************************| 35884 KB 00:00 ETA 226 Transfer complete. 36746099 bytes received in 3.45 seconds (10.17 MB/s) 2. Sending host with the above script running: Speed 185.48 KB/s ftp> get aa local: aa remote: aa 227 Entering Passive Mode (192,168,18,2,156,79) 150 Opening BINARY mode data connection for 'aa' (36746099 bytes). 100% |**********************************************************************| 35884 KB 00:00 ETA 226 Transfer complete. 36746099 bytes received in 193.47 seconds (185.48 KB/s) 3. Same as 2. but script runs with idprio 5: 689.14 KB/s ftp> get aa local: aa remote: aa 227 Entering Passive Mode (192,168,18,2,156,78) 150 Opening BINARY mode data connection for 'aa' (36746099 bytes). 100% |**********************************************************************| 35884 KB 00:00 ETA 226 Transfer complete. 36746099 bytes received in 52.07 seconds (689.14 KB/s) 4. Receiving host with the above script running: Speed 949.32 KB/s ftp> get aa local: aa remote: aa 227 Entering Passive Mode (192,168,18,2,156,84) 150 Opening BINARY mode data connection for 'aa' (36746099 bytes). 100% |**********************************************************************| 35884 KB 00:00 ETA 226 Transfer complete. 36746099 bytes received in 37.80 seconds (949.32 KB/s) 5. Same as 4. but script runs with idprio 5: Speed 991.28 KB/s ftp> get aa local: aa remote: aa 227 Entering Passive Mode (192,168,18,2,156,83) 150 Opening BINARY mode data connection for 'aa' (36746099 bytes). 100% |**********************************************************************| 35884 KB 00:00 ETA 226 Transfer complete. 36746099 bytes received in 36.20 seconds (991.28 KB/s) So we get: no process : 10170 KB/s sender running : 185 KB/s sender running with idprio 5 : 689 KB/s receiver running : 949 KB/s receiver running with idprio 5: 991 KB/s What bugs me is that the rates are so bad in the both idprio'ed cases. Is there an explanation for that behaviour? Is it possible to catch the case when the system is _really_ idle so my process runs only then? Thanks, -Andre To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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