Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Wed, Apr 24, 2013 at 1:37 AM, Stefan Hajnoczi wrote: > I think what you really want is a "tap" block driver which mirrors > writes to a target device (typically a NBD volume). You can model this > on blkverify or check out Benoit Canet's quorum patches. > > Stefan > An interesting thought, w

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Wed, Apr 24, 2013 at 12:15 PM, Paolo Bonzini wrote: > Il 24/04/2013 18:12, Wolfgang Richter ha scritto: > > In the purest form, not to miss "updates" I'm not OK with it. But, I > think > > that introspection can still _mostly_ work given these relaxed > constraints. > > > > Reordered writes c

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Wed, Apr 24, 2013 at 5:26 AM, Paolo Bonzini wrote: > Il 23/04/2013 20:31, Wolfgang Richter ha scritto: > > On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi > > wrote: > > > > The tracing subsystem is geared towards tracepoint instrumentation > > rather than

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Wed, Apr 24, 2013 at 5:24 AM, Paolo Bonzini wrote: > Il 24/04/2013 10:37, Stefan Hajnoczi ha scritto: > >> > Has there been any performance analysis of drive-mirror (impact on > executing guest)? > > What Stefan wrote is about block-backup. > > drive-mirror has a limited impact on guest perfor

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Wed, Apr 24, 2013 at 4:39 AM, Stefan Hajnoczi wrote: > On Tue, Apr 23, 2013 at 03:11:26PM -0400, Wolfgang Richter wrote: > > On Tue, Apr 23, 2013 at 2:31 PM, Wolfgang Richter > wrote: > > > > > On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi >wrote: > > > > > >> Eric's suggestion to use NBD

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Wed, Apr 24, 2013 at 4:37 AM, Stefan Hajnoczi wrote: > > Has there been any performance analysis of drive-mirror (impact on > executing guest)? > > It slows down guest I/O for a couple of reasons: > > 1. Writes now require a read from the original device followed by a >write to the target

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

Il 23/04/2013 20:31, Wolfgang Richter ha scritto: > On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi > wrote: > > The tracing subsystem is geared towards tracepoint instrumentation > rather than binary dumps. > > Can you share some specific applications? >

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

Il 24/04/2013 10:37, Stefan Hajnoczi ha scritto: >> > Has there been any performance analysis of drive-mirror (impact on >> > executing guest)? What Stefan wrote is about block-backup. drive-mirror has a limited impact on guest performance, but it doesn't pass the writes through to the channel.

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Tue, Apr 23, 2013 at 03:11:26PM -0400, Wolfgang Richter wrote: > On Tue, Apr 23, 2013 at 2:31 PM, Wolfgang Richter wrote: > > > On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi wrote: > > > >> Eric's suggestion to use NBD makes sense to me. The block-backup code > >> can be extended fairly ea

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Tue, Apr 23, 2013 at 01:40:19PM -0400, Wolfgang Richter wrote: > > -- > Wolf > > On Apr 23, 2013, at 1:22 PM, Eric Blake wrote: > > > On 04/23/2013 11:12 AM, Wolfgang Richter wrote: > >> I'm interested in adding introspection of disk writes to QEMU for various > >> applications and research

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

-- Wolf On Apr 23, 2013, at 1:22 PM, Eric Blake wrote: > On 04/23/2013 11:12 AM, Wolfgang Richter wrote: >> I'm interested in adding introspection of disk writes to QEMU for various >> applications and research potential. >> >> What I mean by introspection of disk writes is that, when enabled,

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Tue, Apr 23, 2013 at 2:31 PM, Wolfgang Richter wrote: > On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi wrote: > >> Eric's suggestion to use NBD makes sense to me. The block-backup code >> can be extended fairly easier using sync mode=none (do not perform a >> background copy of the entire d

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Tue, Apr 23, 2013 at 2:21 PM, Stefan Hajnoczi wrote: > The tracing subsystem is geared towards tracepoint instrumentation > rather than binary dumps. > > Can you share some specific applications? > Well, my main application is in exposing a "cloud-inotify" service by interpreting sector write

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Tue, Apr 23, 2013 at 7:12 PM, Wolfgang Richter wrote: > I'm interested in adding introspection of disk writes to QEMU for various > applications and research potential. > > What I mean by introspection of disk writes is that, when enabled, each > write > passing through QEMU to backing storage

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On Tue, Apr 23, 2013 at 7:22 PM, Eric Blake wrote: > On 04/23/2013 11:12 AM, Wolfgang Richter wrote: >> I'm interested in adding introspection of disk writes to QEMU for various >> applications and research potential. >> >> What I mean by introspection of disk writes is that, when enabled, each >>

Re: [Qemu-devel] Adding Disk-Level Introspection to QEMU

On 04/23/2013 11:12 AM, Wolfgang Richter wrote: > I'm interested in adding introspection of disk writes to QEMU for various > applications and research potential. > > What I mean by introspection of disk writes is that, when enabled, each > write > passing through QEMU to backing storage would als

[Qemu-devel] Adding Disk-Level Introspection to QEMU

I'm interested in adding introspection of disk writes to QEMU for various applications and research potential. What I mean by introspection of disk writes is that, when enabled, each write passing through QEMU to backing storage would also be copied to an introspection channel for further analysis