On Wed, Dec 03, 2014 at 08:47:21PM -0500, Josef 'Jeff' Sipek via illumos-zfs wrote: > On Wed, Dec 03, 2014 at 05:41:31PM -0800, Matthew Ahrens wrote: > > On Wed, Dec 3, 2014 at 5:37 PM, Josef 'Jeff' Sipek via illumos-zfs < > > [email protected]> wrote: > > > > > So, the reason I managed to find this is because I tried to remove the > > > global dbuf hash table - making use of the per-dnode dbuf avl trees to > > > find > > > dbufs. > > > > I imagine that the performance impact of this would be significant. > > Looking up dbufs is in the hot path of cached reads, and is currently > > O(1). Your change would make it O(log(number of dbufs in this dnode)). > > Yeah, I'd expect it to really depend on the access pattern. Anyway, it's > relatively easy to rip out the hash and see it suck ;) >
Out of curiosity, why are you attempting such a change? What's the motivation? -- Cheers, Prakash > Jeff. > > -- > All parts should go together without forcing. You must remember that the > parts you are reassembling were disassembled by you. Therefore, if you > can’t get them together again, there must be a reason. By all means, do not > use a hammer. > — IBM Manual, 1925 > > > ------------------------------------------- > illumos-zfs > Archives: https://www.listbox.com/member/archive/182191/=now > RSS Feed: https://www.listbox.com/member/archive/rss/182191/26389552-b24035d4 > Modify Your Subscription: > https://www.listbox.com/member/?member_id=26389552&id_secret=26389552-cf0a6444 > Powered by Listbox: http://www.listbox.com _______________________________________________ developer mailing list [email protected] http://lists.open-zfs.org/mailman/listinfo/developer
