Messages in this thread | | | Date | Fri, 02 Aug 2002 17:31:45 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Rmap speedup |
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Rik van Riel wrote: > > On Fri, 2 Aug 2002, Andrew Morton wrote: > > Daniel Phillips wrote: > > > > > > This patch eliminates about 35% of the raw rmap setup/teardown overhead by > > > adopting a new locking interface that allows the add_rmaps to be batched in > > > copy_page_range. > > > > Well that's fairly straightforward, thanks. Butt-ugly though ;) > > It'd be nice if the code would be a bit more beautiful and the > reverse mapping scheme more modular.
I changed it to, essentially:
foo() { spinlock_t *rmap_lock = NULL; unsigned rmap_lockno = -1; ... for (stuff) { cached_rmap_lock(page, &rmap_lock, &rmap_lockno); __page_add_rmap(page, ptep); .. } drop_rmap_lock(&rmap_lock, &rmap_lockno); }
See http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.30/daniel-rmap-speedup.patch
Fixing zap_pte_range pretty much requires the pagemap_lru_lock rework; otherwise we couldn't hold the rmap lock across tlb_remove_page().
> Remember that we're planning to go to an object-based scheme > later on, turning the code into a big monolithic mesh really > makes long-term maintenance a pain...
We have short-term rmap problems:
1) Unexplained pte chain state with ntpd 2) 10-20% increased CPU load in fork/exec/exit loads 3) system lock under heavy mmap load 4) ZONE_NORMAL pte_chain consumption
Daniel and I are on 2), Bill is on 4) (I think). - 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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