* Nadav Amit <namit@xxxxxxxxxx> wrote:
> > On Dec 4, 2018, at 5:34 PM, Nadav Amit <namit@xxxxxxxxxx> wrote:
> >
> > A following patch is going to make module allocated memory
> > non-executable. This requires to modify ftrace and make the memory
> > executable again after it is configured.
> >
> > In addition, this patch makes ftrace use the general text poking
> > infrastructure instead ftrace's homegrown text patching. This provides
> > the advantages of having slightly "safer" code patching and avoiding
> > races with module removal or other mechanisms that patch the kernel
> > code.
> >
> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> > Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>
> > ---
> > arch/x86/kernel/ftrace.c | 74 +++++++++++++---------------------------
> > 1 file changed, 23 insertions(+), 51 deletions(-)
>
> Steven Rostedt pointed that using text_poke() instead of
> probe_kernel_write() would introduce considerable overheads. Running:
>
> # time { echo function > current_tracer; }
>
> takes 0.24s without this patch and 0.7s with. I don’t know whether to
> consider it “so bad”. Obviously we can introduce a batching mechanism and/or
> do some micro-optimization (the latter will not buy us much though).
This should definitely not regress, so can we try the batching approach?
Thanks,
Ingo
