On 1/17/15 22:03 , Greg Zartman wrote: > On Sat, Jan 17, 2015 at 9:53 PM, Robert Mustacchi <[email protected]> wrote: > >> >> In this case, you need to make sure you're doing an apples to oranges >> comparison. By default all disk I/O that a KVM instance does is >> synchronous I/O. If your test in the global zone isn't doing synchronous >> I/O, then it's not going to be a like for like comparison. How are you >> performing your comparisons? >> > > I was doing a real simple : sync; dd if=/dev/zero of=tempfile bs=1M count= > 1024; sync
This is performing asynchronous I/O, not synchronous. To get more of a comparison of what's going on in the guest, in the host, add 'oflag=sync' to the dd command. > This machine doesn't have an SSD slog, so maybe it needs one. It'll certainly help, but to confirm that you should validate with tools like iostat, vfsstat, and DTrace and confirm that you're seeing latency due to disk I/O. Robert ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
