On 31-05-17 22:23, Adrian Chadd wrote: > On 31 May 2017 at 13:20, Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx> wrote: >> On 31-05-17 14:16, Kalle Valo wrote: >>> Adrian Chadd <adrian@xxxxxxxxxxx> writes: >>> >>>> This adds a few configurable debugging options: >>>> >>>> * driver debugging and tracing is now configurable per device >>>> * driver debugging and tracing is now configurable at runtime >>>> * the debugging / tracing is not run at all (besides a mask check) >>>> unless the specific debugging bitmap field is configured. >>>> >>>> Signed-off-by: Adrian Chadd <adrian@xxxxxxxxxxx> >>> >>> [...] >>> >>>> --- a/drivers/net/wireless/ath/ath10k/core.c >>>> +++ b/drivers/net/wireless/ath/ath10k/core.c >>>> @@ -2444,6 +2444,8 @@ struct ath10k *ath10k_core_create(size_t priv_size, struct device *dev, >>>> ar->hw_rev = hw_rev; >>>> ar->hif.ops = hif_ops; >>>> ar->hif.bus = bus; >>>> + ar->debug_mask = ath10k_debug_mask; >>>> + ar->trace_debug_mask = ath10k_debug_mask; >>> >>> Until now tracing has been always enabled, irrespective what debug_mask >>> has contained. Now you are changing that and by default log messages are >>> not delivered through tracing until user enables them. So I think to >>> keep the old behaviour trace_debug_mask should be ATH10K_DBG_ANY >>> (0xffffffff) by default and the user can modify the mask per device via >>> the debugfs file. >>> >>> But is it really needed to be able to filter trace messages? debug_mask >>> I understand, but not sure about trace_debug_mask. >> >> FWIW, in brcmfmac I decided not to filter trace messages. The overhead >> is relatively small and if needed you can pass filter expressions with >> trace-cmd record. > > The reason for configuring it via a mask is that: > > * the previous behaviour is "always call debug(), conditionally print, > always pass to trace" > > This meant that function arguments were evaluated even if things > weren't being printed. > > So to avoid that in the default case, there are now two masks. If I > have one mask then I can only trace what is being printed, which is > not desired. I'd like to be able to have no overhead when doing no > debugging, a little overhead when doing tracing (and only the items > being traced), and then printing when I want to print. Well, it is up to you. Have to clariy though that if you are not actually recording a trace there is (almost) no overhead. We have Kconfig to compile tracing code in and I see no performance impact with tracing code. Only when doing tracing you will get little overhead. Regards, Arend > -adrian >
