Date: Thu, 11 Nov 1999 21:00:42 -0700 (MST) From: "Kenneth D. Merry" <ken@kdm.org> To: shimon@simon-shapiro.org (Simon Shapiro) Cc: rjesup@wgate.com (Randell Jesup), freebsd-arch@freebsd.org Subject: Re: I/O Evaluation Questions (Long but interesting!) Message-ID: <199911120400.VAA31700@panzer.kdm.org> In-Reply-To: <382B8C18.DD84F967@simon-shapiro.org> from Simon Shapiro at "Nov 11, 1999 10:40:08 pm"
next in thread | previous in thread | raw e-mail | index | archive | help
Simon Shapiro wrote... > "Kenneth D. Merry" wrote: > > > > [ Simon: the "charset = " (i.e. nothing) line your mail makes my mailer > > barf. You may want to adjust your character set. ] > [ Am using Netscape Messenger. Know not how to do that > (no relevant preference found :-( ] My best guess is, go to: Edit -> Preferences -> Navigator -> Languages And make sure you at least have English defined there. Also, go to: View -> Character Set And make sure you've got Western (ISO-8559-1) defined. > > Simon Shapiro wrote... > > > Randell Jesup wrote: > > > > Unlikely, though, and very tricky. (Interesting idea, though - > > > > pseudo-mmap.) They also could set up the DMA, and mark the pages in the > > > > page table so that you'll fault if you try to access them, and then undo > > > > the mark when the IO is done (or as each N pages of the IO is done make > > > > those N pages accessible). There are many cute tricks here... > > > > > > > > What hardware do you have that gives 100MB/s or more??? > > > > > > (bragging corner: 167 read, 138 write :-) DPT PM3755U2B with > > > 256MB of ECC cache in a Dell PowerEdge 1300/600. > > > FreeBSD RELENG_3, single CPU running. > > > > How can you get speeds like that with just a 32-bit PCI bus? The specs for > > the PowerEdge 1300 say it has 5 32-bit PCI slots: > > These numbers are for block devices. The kernel obviously > caches some of this. I should look next time at emory usage; > The machine has 1GB of memory. The dataset is about 15GB per > array. Is that for random or sequential I/O? With sequential I/O, you would probably blow away any caching effects. With random I/O, though, you might get significant help from the cache, especially with that much RAM. > I am getting about 120MB/Sec form the PCI > bus. I can believe that. > Raw disks perfromance is totally throttled by physics; > We are running at about 200% of Seagate specs. How can you run at 200% of the spec? Most of the time disk manufacturers are even a little optimistic about their high end performance. > I am running into some strange situations. Perhaps some > light can be shed; Sorry, no clue there. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199911120400.VAA31700>