On Wed, Sep 19, 2018 at 12:49:15PM -0600, Jens Axboe wrote: > On 9/19/18 12:25 PM, Dennis Zhou wrote: > > As we explore stacking traces, it is nice to be able to scale a trace to > > understand how the traces end up interacting. > > > > This patch adds scaling by letting the user pass in percentages to scale > > a trace by. When passed '--merge_blktrace_scalars="100", the trace is > > ran at 100% speed. If passed 50%, this will halve the trace timestamps. > > The new option takes in a comma separated list that index-wise pairs > > with the passed files in "--read_iolog". > > How is this different than replay_time_scale? > I think merge_blktrace_scalars is a trace building parameter whereas replay_time scale is a runtime parameter. merge_blktrace_scalars is an index-paired list with the logs passed to --read_iolog allowing for each trace to be independently scaled. replay_time_scale happens at runtime and scales the entire trace uniformly. And because replay_time_scale happens at runtime, I'm not sure repurposing the numbers would be super intuitive. Thanks, Dennis
