On Wed, 2009-01-21 at 20:47 -0200, Arnaldo Carvalho de Melo wrote: > Em Thu, Jan 22, 2009 at 09:36:53AM +1100, Greg Banks escreveu: > > Chuck Lever wrote: > > > > > > > > > I think we need to visit this issue on a case-by-case basis. > > > Sometimes dprintk is appropriate. Sometimes printk(KERN_ERR). > > > Sometimes a performance metric. > > Well said. > > > > > Trond has always maintained that dprintk() is best for developers, but > > > probably inappropriate for field debugging, > > It's not a perfect tool but it beats nothing at all. > > > and I think that may also > > > apply to trace points. > > It depends on whether distros can be convinced to enable it by default, > > and install by default any necessary userspace infrastructure. The > > most important thing for field debugging is Just Knowing that you have > > all the bits necessary to perform useful debugging without having to > > find some RPM that matches the kernel that the machine is actually > > running now, and not the one that was present when the machine was > > installed. > > Exactly, that is why an ftrace plugin, that only when selected using > echo "nfs" > /debug/tracing/current_tracer will activate the tracepoints > and provide output via /debug/tracing/trace or /deb/tracing/trace_pipe, > possibly combined with other ftrace plugins such as the stacktrace, > blktrace, etc. > > I.e. no need at all for any matching userspace tool, near zero impact > when not activated, useful, if done right, for both developers and for > admins. > > Again, an example can be found in the blktrace ftrace plugin[1], that > instead of adding a requirement will eventually drop an existing, well > established one (blktrace(8)). I must be missing something. Exactly what functionality does this then give us that we don't have already with the existing RPC/NFS dprintk() scheme? Trond -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
