lkml.org 
[lkml]   [1999]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: How to make Linux scale up WRT bandwidth and size?
Date
> frames per second.  This means a sustained rate of roughly 10MB per
> second. Lossy compression would falsify the results and is thus not

Thats about the bandwidth of a disk

> even be enough for colour pictures (which would, however, probably
> demand using a RAID controller for the RAID array of disks instead of
> the single Ultrawide SCSI bus topping out at 40MBps). Trying to find
> a controller that would use a 64bit PCI-slot would not be a bad idea,
> either.

Software striping will do you nicely, 64bit pci scsi cards are
easy to get.

> Now how to do the recording? The easiest solution would probably be
> memory-mapping a recording file and doing a single large read-call
> from the framegrabber (video4linux device) to the file.

Or memory map the frame grabber and write to the file - thats how the
existing video4linux rtjpeg tools work

> Will this be able to provide the necessary sustained performance that
> the hardware is principally capable of providing? I doubt it yet, but
> I need a more qualified opinion.

It ought to.

> File size: the ext2 file system tops out at 2GB file size, which is

Not on a 64bit machine like the Alpha

> Efficiency of memory map: will all that happens in that scenario be a
> transfer from framegrabber to memory in one copy done in busmaster
> mode by the framegrabber, and from memory to disk in another busmaster
> done by the SCSI controller? Is there even a possibility that a

Right now you can set it up so that you DMA from the capture card to
the memory and then write it ought through the buffer cache. Stephen
Tweedie has O_DIRECT patches for Linux (I dont know how tested they are
on Alpha but they survive Oracle on x86 so ..) that willl mean you are
doing DMA direct back out from the same memory

Alan



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:51    [W:0.104 / U:0.372 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site