lkml.org 
[lkml]   [2007]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: remove global locks from mm/highmem.c

* Christoph Hellwig <hch@infradead.org> wrote:

> On Sun, Jan 28, 2007 at 04:17:00PM +0100, Ingo Molnar wrote:
> > scalability. I did lock profiling on the -rt kernel, which exposes
> > such things nicely. Half of the lock contention events during kernel
> > compile were due to kmap(). (The system had 2 GB of RAM, so 40%
> > lowmem, 60% highmem.)
>
> Numbers please, and not on -rt but on mainline. Please show the
> profiles.

i'm sorry, but do you realize that files_lock is a global lock,
triggered by /every single/ file close?

" files_lock is a global lock and we touch it for every single
sys_close() system call that the system does. "

You really dont need to be a rocket scientist to see that it's a
globally bouncing cacheline that has a major effect on certain
VFS-intense workloads. Peter has worked hard to eliminate its effects
without having to couple this to an intrusive rewrite of the TTY layer.

( really, i personally find your dismissive style apalling and i think
such a reception of a nice patchset must be humiliating to Peter. I
certainly try to avoid to be involved with any VFS internals, due to
this unwelcoming tone of discussion. Had you been around when i
started contributing to the Linux kernel i'd probably not be hacking
the kernel today. You are a good hacker but the simultaneous
collateral damage you are causing is significantly reducing the net
benefit. )

> > ps. please fix your mailer to not emit Mail-Followup-To headers. In
> > Mutt you can do this via "set followup_to=no" in your .muttrc.
>
> I have told you last time that this is absolutely intentional and I
> won't change it.

( You are messing up the reply headers, everyone is listed in the 'To:'
field for any reply to your mail, instead of being added to the Cc:
list. )

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

\
 
 \ /
  Last update: 2007-01-28 16:53    [W:0.058 / U:3.692 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site