>> > On Mon, 27 Jun 2005, Chen, Kenneth W wrote: >> > > I don't recall seeing tree_lock to be a problem for DSS workload either. >> > >> > I have seen the tree_lock being a problem a number of times with large >> > scale NUMA type workloads. >> >> I totally agree! My earlier posts are strictly referring to industry >> standard db workloads (OLTP, DSS). I'm not saying it's not a problem >> for everyone :-) Obviously you just outlined a few .... > > I'm a bit late to the party here (was gone on vacation), but I do have > profiles from DSS workloads using page-cache rather than O_DIRECT and > I do see spin_lock_irq() in the profiles which I'm pretty certain are > locks spinning for access to the radix_tree. I'll talk about it a bit > more up in Ottawa but here's the top 5 on my profile (sorry don't have > the number of ticks at the momement): > > 1. dedicated_idle (waiting for I/O) > 2. __copy_tofrom_user > 3. radix_tree_delete > 4. _spin_lock_irq > 5. __find_get_block > > So, yes, if the page-cache is used in a DSS workload then one will see > the tree-lock. BTW, this was on a PPC64 machine w/ a fairly small > NUMA factor.
The easiest way to confirm the spin-lock thing is to recompile with CONFIG_SPINLINE, and take a new profile, then diff the two ... M. - 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/
