This is the mail archive of the mailing list for the GDB project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] Call target_can_download_tracepoint if there are tracepoints to download

On 09/08/2015 03:13 PM, Yao Qi wrote:
> Nowadays, GDB calls target_can_download_tracepoint at the entry of
> download_tracepoint_locations, which is called by.
> update_global_location_list.  Sometimes, it is not needed to call
> target_can_download_tracepoint at all because there is no tracepoint
> created.  In remote target, target_can_download_tracepoint send
> qTStatus to the remote in order to know whether tracepoint can be
> downloaded or not.  This means some redundant qTStatus packets are
> sent.
> This patch is to teach GDB to call target_can_download_tracepoint
> lazily, only on the moment there are tracepoint to download.
> gdb.perf/single-step.exp (with a local patch to measure RSP packets)
> shows the number of RSP packets is reduced because there is no
> tracepoint at all, so GDB doesn't send qTStatus any more.
>                        # of RSP packets
>                        original  patched
> single-step rsp 1000   7000      6000
> single-step rsp 2000   14000     12000
> single-step rsp 3000   21000     18000
> single-step rsp 4000   28000     24000
> Regression tested on x86_64-linux, both native and gdbserver.

Awesome.  These qTStatus packets have bothered me before too.

The patch looks fine to me.

> gdb:
> 2015-09-08  Yao Qi  <>
> 	* breakpoint.c (download_tracepoint_locations): New local
> 	can_download_tracepoint.  Check the result of
> 	target_can_download_tracepoint and save it in
> 	can_download_tracepoint if there are tracepoints to download.
> 	* linux-nat.h (enum tribool): Move it to ...
> 	* defs.h: ... here.

I'd suggest moving tribool in common/common-types.h.  It's just
be a matter of time before we want to use this in gdbserver too..

Pedro Alves

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]