Re: [parisc-linux] rmap: parisc __flush_dcache_page

[Andrea Arcangeli <andrea@suse.de>]

On Thu, Apr 08, 2004 at 01:07:31PM -0500, James Bottomley wrote:
> On Thu, 2004-04-08 at 12:51, Andrea Arcangeli wrote:
> > that path can take as long as timeslice to run, not taking interrupts
> > for a whole scheduler timeslice is pretty bad.
> 
> OK, now I'm confused.  Where's the whole timeslice bit coming from? the
> parisc flush_dcache_code better not take a timeslice to execute
> otherwise we're in very serious performance trouble.
> 
> Does it take as long as a timeslice to do mmap[_shared] list insertion?

it enterely depends on the workload. On a desktop machine there may be
only some hundred entries in those lists at maximum with glibc being the
biggest offender:

cat /proc/*/maps | grep libc.so.6 | wc -l

with shared memory on some server there can be easily several thousand
entries for some inode even on 64bit, but a timeslice was probably
exaggerated (the timeslice was for the walking of the ptes in each
mapping too, I don't think you need to look at every pte).