Date: Mon, 27 Jan 2003 00:17:24 -0500 (EST) From: "Ashutosh S. Rajekar" <asr@softhome.net> To: Sean Hamilton <sh@bel.bc.ca> Cc: <hackers@FreeBSD.ORG> Subject: Re: Random disk cache expiry Message-ID: <Pine.LNX.4.33.0301270013250.1638-100000@vangogh> In-Reply-To: <001801c2c5c0$5666de10$16e306cf@slugabed.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, 26 Jan 2003, Sean Hamilton wrote: > > In my case I have a webserver serving up a few dozen files of about 10 MB > each. While yes it is true that I could purchase more memory, and I could > purchase more drives and stripe them, I am more interested in the fact that > this server is constantly grinding away because it has found a weakness in > the caching algorithm. > > After further thought, I propose something much simpler: when the kernel is > hinted that access will be sequential, it should stop caching when there is > little cache space available, instead of throwing away old blocks, or be > much more hesitant to throw away old blocks. Consider that in almost all > cases where access is sequential, as reading continues, the chances of the > read being aborted increase: ie, users downloading files, directory tree > traversal, etc. Since the likelihood of the first byte reading the first > byte is very high, and the next one less high, and the next less yet, etc, > it seems to make sense to tune the caching algorithm to accomodate this. Your case seems to be a highly specific one, and would require very specific tuning. And then one will be able to find some other "unwanted behaviour" once you tune your system for particular behaviour. -ASR http://www.crosswinds.net/~rajekar MERYL STREEP is my obstetrician! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.LNX.4.33.0301270013250.1638-100000>