On Thu, Jan 20, 2005 at 11:00:16PM -0800, Andrew Morton wrote: > Last time we dicsussed this you pointed out that reserving more lowmem from > highmem-capable allocations may actually *help* things. (Tries to remember > why) By reducing inode/dentry eviction rates? I asked Martin Bligh if he > could test that on a big NUMA box but iirc the results were inconclusive.
This is correct, guaranteeing more memory to be freeable in lowmem (ptes aren't freeable without a sigkill for example) the icache/dcache will at least have a margin where it can grow indipendently from highmem allocations. > Maybe it just won't make much difference. Hard to say. I don't know myself if it makes a performance difference, all old benchmarks have been run with this applied. This was applied for correcntess (i.e. to avoid sigkills or lockups), it wasn't applied for performance. But I don't see how it could hurt performance (especially given current code already does the check at runtime, which is pratically the only fast-path cost ;). > > The sysctl name had to change to lowmem_reserve_ratio because its > > semantics are completely different now. > > That reminds me. Documentation/filesystems/proc.txt ;) Woops, forgotten about it ;) > I'll cook something up for that. Thanks. If you prefer I can write it too to relieve you from this load, it's up to you. If you want to fix it yourself go ahead of course ;) - 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/
