William Lee Irwin III wrote:
>
> Paolo Ciarrocchi wrote:
> >> Hi all,
> >> I've just ran lmbench2.0 on my laptop.
> >> Here the results (again, 2.5.33 seems to be "slow", I don't know why...)
>
> On Sat, Sep 07, 2002 at 09:20:56AM -0700, Andrew Morton wrote:
> > The fork/exec/mmap slowdown is the rmap overhead. I have some stuff
> > which partialy improves it.
>
> Hmm, Where does it enter the mmap() path? PTE instantiation is only done
> for the VM_LOCKED case IIRC. Otherwise it should be invisible.
>
lat_mmap seems to do a mmap, faults in ten pages and then
a munmap(). Most of the CPU cost is in cache misses against
the pagetables in munmap().
c012d54c 153 0.569493 do_mmap_pgoff
c012db5c 158 0.588104 find_vma
c01301ec 172 0.640214 filemap_nopage
c0134e84 172 0.640214 release_pages
c0114744 184 0.684881 smp_apic_timer_interrupt
c012ce3c 248 0.9231 handle_mm_fault
c012f738 282 1.04965 find_get_page
c013e2b0 356 1.32509 __set_page_dirty_buffers
c0116294 377 1.40326 do_page_fault
c013e72c 383 1.42559 page_add_rmap
c013e8bc 398 1.48143 page_remove_rmap
c012cb10 425 1.58193 do_no_page
c0109d70 629 2.34125 page_fault
c012b2f4 1036 3.85618 zap_pte_range
c0107048 20205 75.2066 poll_idle
(Multiply everything by four - it's a quad)
Instruction-level profile for -mm5:
c012b2f4 1036 3.85618 0 0 zap_pte_range /usr/src/25/mm/memory.c:325
c012b2f5 2 0.19305 0 0 /usr/src/25/mm/memory.c:325
c012b2fd 1 0.0965251 0 0 /usr/src/25/mm/memory.c:325
c012b300 2 0.19305 0 0 /usr/src/25/mm/memory.c:325
c012b306 1 0.0965251 0 0 /usr/src/25/mm/memory.c:329
c012b309 1 0.0965251 0 0 /usr/src/25/mm/memory.c:329
c012b30f 1 0.0965251 0 0 /usr/src/25/mm/memory.c:331
c012b319 1 0.0965251 0 0 /usr/src/25/mm/memory.c:331
c012b340 1 0.0965251 0 0 /usr/src/25/mm/memory.c:336
c012b348 1 0.0965251 0 0 /usr/src/25/include/asm/highmem.h:80
c012b350 1 0.0965251 0 0 /usr/src/25/include/asm/thread_info.h:75
c012b35a 2 0.19305 0 0 /usr/src/25/include/asm/highmem.h:85
c012b365 2 0.19305 0 0 /usr/src/25/include/asm/highmem.h:86
c012b3c3 2 0.19305 0 0 /usr/src/25/mm/memory.c:337
c012b3d6 1 0.0965251 0 0 /usr/src/25/mm/memory.c:338
c012b3e9 3 0.289575 0 0 /usr/src/25/mm/memory.c:341
c012b3f5 106 10.2317 0 0 /usr/src/25/mm/memory.c:342
c012b3f8 2 0.19305 0 0 /usr/src/25/mm/memory.c:342
c012b3fa 26 2.50965 0 0 /usr/src/25/mm/memory.c:343
c012b3fc 124 11.9691 0 0 /usr/src/25/mm/memory.c:343
c012b405 13 1.25483 0 0 /usr/src/25/mm/memory.c:345
c012b40b 1 0.0965251 0 0 /usr/src/25/mm/memory.c:346
c012b410 2 0.19305 0 0 /usr/src/25/mm/memory.c:348
c012b412 1 0.0965251 0 0 /usr/src/25/mm/memory.c:348
c012b414 62 5.98456 0 0 /usr/src/25/mm/memory.c:349
c012b41b 1 0.0965251 0 0 /usr/src/25/mm/memory.c:350
c012b421 21 2.02703 0 0 /usr/src/25/mm/memory.c:350
c012b427 2 0.19305 0 0 /usr/src/25/mm/memory.c:351
c012b432 2 0.19305 0 0 /usr/src/25/include/asm/bitops.h:244
c012b434 10 0.965251 0 0 /usr/src/25/mm/memory.c:352
c012b437 1 0.0965251 0 0 /usr/src/25/mm/memory.c:352
c012b43d 5 0.482625 0 0 /usr/src/25/mm/memory.c:353
c012b446 7 0.675676 0 0 /usr/src/25/include/linux/mm.h:389
c012b44b 1 0.0965251 0 0 /usr/src/25/include/linux/mm.h:392
c012b44e 1 0.0965251 0 0 /usr/src/25/include/linux/mm.h:392
c012b451 7 0.675676 0 0 /usr/src/25/include/linux/mm.h:393
c012b453 2 0.19305 0 0 /usr/src/25/include/linux/mm.h:393
c012b461 6 0.579151 0 0 /usr/src/25/include/linux/mm.h:396
c012b466 8 0.772201 0 0 /usr/src/25/include/linux/mm.h:396
c012b46f 6 0.579151 0 0 /usr/src/25/mm/memory.c:356
c012b476 15 1.44788 0 0 /usr/src/25/include/asm-generic/tlb.h:105
c012b481 3 0.289575 0 0 /usr/src/25/include/asm-generic/tlb.h:106
c012b490 5 0.482625 0 0 /usr/src/25/include/asm-generic/tlb.h:110
c012b493 7 0.675676 0 0 /usr/src/25/include/asm-generic/tlb.h:110
c012b49a 1 0.0965251 0 0 /usr/src/25/include/asm-generic/tlb.h:110
c012b49d 3 0.289575 0 0 /usr/src/25/include/asm-generic/tlb.h:110
c012b4a0 1 0.0965251 0 0 /usr/src/25/include/asm-generic/tlb.h:110
c012b4a3 8 0.772201 0 0 /usr/src/25/include/asm-generic/tlb.h:111
c012b4aa 13 1.25483 0 0 /usr/src/25/include/asm-generic/tlb.h:111
c012b500 128 12.3552 0 0 /usr/src/25/mm/memory.c:341
c012b504 108 10.4247 0 0 /usr/src/25/mm/memory.c:341
c012b50b 111 10.7143 0 0 /usr/src/25/mm/memory.c:341
c012b50e 99 9.55598 0 0 /usr/src/25/mm/memory.c:341
c012b511 86 8.30116 0 0 /usr/src/25/mm/memory.c:341
c012b51c 4 0.3861 0 0 /usr/src/25/include/asm/thread_info.h:75
c012b521 3 0.289575 0 0 /usr/src/25/mm/memory.c:366
c012b525 1 0.0965251 0 0 /usr/src/25/mm/memory.c:366
c012b526 1 0.0965251 0 0 /usr/src/25/mm/memory.c:366
So it's a bit of rmap in there. I'd have to compare with a 2.4
profile and fiddle a few kernel parameters. But I'm not sure
that munmap of extremely sparsely populated pagtetables is very
interesting?
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This archive was generated by hypermail 2b29 : Sun Sep 15 2002 - 22:00:14 EST