| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] [PATCH][TOOLS] Reducing impact ofdomainsave/restore/dump
Hi,
I also read somewhere (either the man page or in the code) that the
sync is necessary for exactly these reasons.
robert
On Feb 21, 2007, at 07:22, Graham, Simon wrote:
Do you need the fsync at all? It's possible that the kernel will
launder-then-discard the affected pages automatically, just from the
fadvise() alone.
To be honest, I'm not completely sure; the implementation of the
fadvise
call triggers a write back and then explicitely discards any clean
pages
-- I don't _think_ it will discard clean pages once the write back
completes (but it's not entirely clear to me how much of the write
back
is done synchronously).
However, it definitely makes a perf difference if you explicitely
fsync
before each call to fadvise -- therefore I believe that the fadvise
call
is definitely not cleaning all the pages inline (which would be
equivalent to the fsync()).
So -- my belief is that without the fsync, there will be some (clean)
pages for the file still in the cache when this is done; my goal
was to
remove ALL the pages, but perhaps leaving a few lying around is OK..
/simgr
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home