Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 27 Apr 2006 15:22:37 +1000 | From | Nick Piggin <> | Subject | Re: Lockless page cache test results |
| |
Andrew Morton wrote:
>>The top of the 4-client >>vanilla run profile looks like this: >> >>samples % symbol name >>65328 47.8972 find_get_page >> >>Basically the machine is fully pegged, about 7% idle time. > > > Most of the time an acquisition of tree_lock is associated with a disk > read, or a page-size memset, or a page-size memcpy. And often an > acquisition of tree_lock is associated with multiple pages, not just a > single page.
Still, most of the times it is acquired would be once per page for read, write, nopage.
For read and write, often it will be a full page memcpy but even such a memcpy operation can quickly become insignificant compared to tl contention.
Anyway, whatever. What needs to be demonstrated are real world improvements at the end of the day.
> > So although the graph looks good, I wouldn't view this as a super-strong > argument in favour of lockless pagecache.
No. Cool numbers though ;)
-- SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
- 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/
| ![\](/images/icornerr.gif) |