Messages in this thread | | | From | Nick Piggin <> | Subject | Re: Linux 2.6.29 | Date | Fri, 3 Apr 2009 16:05:20 +1100 |
| |
On Friday 03 April 2009 13:16:08 Linus Torvalds wrote: > > On Thu, 2 Apr 2009, Jeff Garzik wrote: > > > > The most interesting thing I found: the SSD does 80 MB/s for the first ~1 GB > > or so, then slows down dramatically. After ~2GB, it is down to 32 MB/s. > > After ~4GB, it reaches a steady speed around 23 MB/s. > > Are you sure that isn't an effect of double and triple indirect blocks > etc? The metadata updates get more complex for the deeper indirect blocks. > > Or just our page cache lookup? Maybe our radix tree thing hits something > stupid. Although it sure shouldn't be _that_ noticeable.
Hmm, I don't know what you have in mind. page cache lookup should be several orders of magnitude faster than a disk can write the pages out?
Dirty/writeout/clean cycle still has to lock the radix tree to change tags, but that's really not going to be significantly contended (nor does it synchronise with simple lookups).
| |