On Tue, 1 Nov 2005, Mel Gorman wrote:
> On Tue, 1 Nov 2005, Dave Hansen wrote:
>
> > On Tue, 2005-11-01 at 07:25 -0800, Martin J. Bligh wrote:
> > > > I really don't think we *want* to say we support higher order allocations
> > > > absolutely robustly, nor do we want people using them if possible. Because
> > > > we don't. Even with your patches.
> > > >
> > > > Ingo also brought up this point at Ottawa.
> > >
> > > Some of the driver issues can be fixed by scatter-gather DMA *if* the
> > > h/w supports it. But what exactly do you propose to do about kernel
> > > stacks, etc? By the time you've fixed all the individual usages of it,
> > > frankly, it would be easier to provide a generic mechanism to fix the
> > > problem ...
> >
> > That generic mechanism is the kernel virtual remapping. However, it has
> > a runtime performance cost, which is increased TLB footprint inside the
> > kernel, and a more costly implementation of __pa() and __va().
> >
> > I'll admit, I'm biased toward partial solutions without runtime cost
> > before we start incurring constant cost across the entire kernel,
> > especially when those partial solutions have other potential in-kernel
> > users.
>
> To give an idea of the increased TLB footprint, I ran an aim9 test with
> cpu_has_pse disabled in include/arch-i386/cpufeature.h to force the use
> of small pages for the physical memory mappings.
>
> This is the -clean results
>
> clean clean-nopse
> 1 creat-clo 16006.00 15294.90 -711.10 -4.44% File Creations and Closes/second
> 2 page_test 117515.83 118677.11 1161.28 0.99% System Allocations & Pages/second
> 3 brk_test 440289.81 436042.64 -4247.17 -0.96% System Memory Allocations/second
> 4 jmp_test 4179466.67 4173266.67 -6200.00 -0.15% Non-local gotos/second
> 5 signal_test 80803.20 78286.95 -2516.25 -3.11% Signal Traps/second
> 6 exec_test 61.75 60.45 -1.30 -2.11% Program Loads/second
> 7 fork_test 1327.01 1318.11 -8.90 -0.67% Task Creations/second
> 8 link_test 5531.53 5406.60 -124.93 -2.26% Link/Unlink Pairs/second
>
> This is what mbuddy-v19 with and without pse looks like
>
> mbuddy-v19 mbuddy-v19-nopse
> 1 creat-clo 15889.41 15328.22 -561.19 -3.53% File Creations and Closes/second
> 2 page_test 117082.15 116892.70 -189.45 -0.16% System Allocations & Pages/second
> 3 brk_test 437887.37 432716.97 -5170.40 -1.18% System Memory Allocations/second
> 4 jmp_test 4179950.00 4176087.32 -3862.68 -0.09% Non-local gotos/second
> 5 signal_test 85335.78 78553.57 -6782.21 -7.95% Signal Traps/second
> 6 exec_test 61.92 60.61 -1.31 -2.12% Program Loads/second
> 7 fork_test 1342.21 1292.26 -49.95 -3.72% Task Creations/second
> 8 link_test 5555.55 5412.90 -142.65 -2.57% Link/Unlink Pairs/second
>
I forgot to include the comparison between -clean and -mbuddy-v19-nopse
clean mbuddy-v19-nopse
1 creat-clo 16006.00 15328.22 -677.78 -4.23% File Creations and Closes/second
2 page_test 117515.83 116892.70 -623.13 -0.53% System Allocations & Pages/second
3 brk_test 440289.81 432716.97 -7572.84 -1.72% System Memory Allocations/second
4 jmp_test 4179466.67 4176087.32 -3379.35 -0.08% Non-local gotos/second
5 signal_test 80803.20 78553.57 -2249.63 -2.78% Signal Traps/second
6 exec_test 61.75 60.61 -1.14 -1.85% Program Loads/second
7 fork_test 1327.01 1292.26 -34.75 -2.62% Task Creations/second
8 link_test 5531.53 5412.90 -118.63 -2.14% Link/Unlink Pairs/second
--
Mel Gorman
Part-time Phd Student Java Applications Developer
University of Limerick IBM Dublin Software Lab
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
