On Thu, 18 Mar 2004, Pat LaVarre wrote: > Agreed, shattering a read/ write stream into miniscule pieces improves > interop at small cost to typical usage of much storage. > > Sorry I mistook the words "I wonder if we shouldn't reduce max_sectors > permanently" as a disavowal of your cogent discussion: > > > We should let people who want more performance tweak the fragment size > > up > > (to a reasonably large limit) if they want to try -- this could lead to > > device failures or better performance. Letting people shoot > > themselves in > > the foot is a long-standing tradition in Linux, but I don't want to > > leave > > the 'non-power users' out in the cold. > > Pat LaVarre
We should put something, maybe on the usb-storage web site, maybe somewhere in the online kernel documentation, explaining to people how they can change max_sectors and what it means. Important points to include: max_sectors should be a multiple of 8 (for maximum efficiency since file I/O tends to be grouped in units of a 4 KB memory page), the minimum legal value is 8, the maximum legal value is 1024. It would also be good to come up with an example showing how a hotplug script can be modified to do this automatically. And lastly we should say that a few devices don't work unless max_sectors <= 32 (or is it 64?), Genesys Logic interfaces (vendor ID = 0x05e3 in /proc/bus/usb/devices) require max_sectors <= 128, a number of devices require max_sectors <= 240, but many (or most) will work with max_sectors = 1024. The devices with limitations tend to be disk drives and maybe card readers; optical devices usually don't need special handling. Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
