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It uses the filesystem’s asynchronous I/O support, rather than using > synchronous I/O. > 2. It bypasses the page cache, removing a redundant layer of caching and > associated overhead. > --- > tools/hotplug/Linux/block | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/hotplug/Linux/block b/tools/hotplug/Linux/block > index 2691b56951c9b82094471a141b9e0bed04abb929..75785f3a5422c4a5f962a4cd4f6acae5080d036d 100644 > --- a/tools/hotplug/Linux/block > +++ b/tools/hotplug/Linux/block > @@ -330,7 +330,7 @@ mount it read-write in a guest domain." > else > roflag='' > fi > - do_or_die losetup $roflag "$loopdev" "$file" > + do_or_die losetup --direct-io=on $roflag "$loopdev" "$file" I guess you want to first check (maybe in tools/configure) that losetup actually supports that option. The old-ish one I'm looking at doesn't, according to its --help output at least. Jan