[Pdbg] [PATCH] Revert "htm: Use splice() to copy dump"

[Michael Neuling]

On Fri, 2020-12-04 at 08:42 +1100, Rashmica Gupta wrote:
> On Tue, 2020-12-01 at 12:25 +1100, Michael Neuling wrote:
> > On Tue, 2020-12-01 at 11:52 +1100, Rashmica Gupta wrote:
> > > On Tue, 2020-12-01 at 11:37 +1100, Michael Neuling wrote:
> > > > On Thu, 2020-11-26 at 13:38 +1100, Rashmica Gupta wrote:
> > > > > This reverts commit 436eb8c74fb4a762b61837ee27ddbd6b5fe21334.
> > > > > Unable to use splice on newer kernels due to 36e2c7421f02 ("fs:
> > > > > don't
> > > > > allow splice read/write without explicit ops"). So revert back
> > > > > to
> > > > > plain
> > > > > old read/write.
> > > > 
> > > > Is there a performance penalty with this and if so how much? 
> > > 
> > > On older kernels most probably, but does it matter when splice just
> > > fails on newer kernels? Do you want to dectect kernel version and
> > > choose whether to use splice or not?
> > 
> > (adding people back on CC)
> > 
> > If the performance hit is particularly bad, then we might want the
> > splice()
> > optimisation, but if it's only a small hit then I wouldn't bother.
> 
> With my eyeball statistics, there is no noticable difference with
> dumping a 1.7GB file.

OK, great, let's not bother with any optimisation the. 

Thanks,
Mikey