Messages in this thread | | | From | Darren Williams <> | Date | Sat, 14 Aug 2004 14:18:15 +1000 | Subject | Re: Serious Kernel slowdown with HIMEM (4Gig) in 2.6.7 |
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Hi Lawrence
On Fri, 13 Aug 2004, Lawrence E. Freil wrote:
> Hello, > > I'm following the kernel bug reporting format so: > > 1. Linux 2.6.7 kernel slowdown in directory access with HIMEM on > > 2. I have discovered an issue with the Linux 2.6.7 kernel when HIMEM is > enabled which exhibits itself as a slowdown in directory access regardless > of filesystem used. When HIMEM is disabled the performance returns to > normal. The test I ran was a simple "/usr/bin/time ls -l" of a directory > with 3000 empty files. With HIMEM enabled in the kernel this takes > approximately 1.5 seconds. Without HIMEM it takes 0.03 seconds. The > time is 100% CPU and no I/O operations are done to disk. "time" reports > there are 460 "minor" page faults with zero "major" page faults. > I believe the issue here is the mapping of pages between high-mem and > lowmem in the kernel paging code. This increase in time for directory > accesses doubles to triples times for applications using samba. > I have also tested this on another system which had only 512Meg of RAM > but with HIMEM set in the kernel and did not experience the problem. > I believe it only effects the performance when the paging buffers end > up in highmem. > > 3. Keywords: HIMEM, Performance > Would you be running these in a gnome-terminal, I remember seeing a thread that discussed gnome-terminal problems though a quick search did not turn anything up. Here is what I get between a xterm and gnome-terminal.
xterm # time ls -lR /etc real 0m0.381s user 0m0.056s sys 0m0.130s
gnome-terminal # time ls -lR /etc real 0m0.869s user 0m0.057s sys 0m0.141s
I ran this twice in both teminals and reported the second result.
system info P4 3.06 HT 2.6.7 SMP/SMT/HIGHMEM 1GB ram
------------------------------------------------- Darren Williams <dsw AT gelato.unsw.edu.au> Gelato@UNSW <www.gelato.unsw.edu.au> -------------------------------------------------- - 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/
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