[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] Use direct I/O for loop devices
On Thu, Aug 18, 2022 at 09:02:11AM +0200, Jan Beulich wrote: > On 17.08.2022 22:46, Demi Marie Obenour wrote: > > This is a huge performance improvement for two reasons: > > > > 1. 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. What version are you referring to? In Qubes OS the current plan is to use a block “script” written in C, to improve performance and (when combined with kernel patches) eliminate race conditions. This code could be made a wrapper for the C version. -- Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab Attachment:
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