Messages in this thread | | | Date | Wed, 21 Dec 2011 21:07:14 -0800 (PST) | From | david@lang ... | Subject | Re: RFC: android logger feedback request |
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On Wed, 21 Dec 2011, Brian Swetland wrote:
> On Wed, Dec 21, 2011 at 8:47 PM, <david@lang.hm> wrote: >> On Wed, 21 Dec 2011, Brian Swetland wrote: >>> Any thoughts as to how one could allow N userspace agents to log to a >>> single shared buffer without one agent, if buggy or malicious, >>> spamming out all the other contents of the log? This is one of the >>> main reasons we maintain separate logs in Android today, and are >>> likely to continue doing so until we figure out how resolve the issue. >> >> note that you still don't prevent one app from blowing out the logs, all you >> do is separate the logs into a handfulof categories and limit the app >> (through standard filesystem permissions) to only blowing out one category >> of logs. >> >> or do I misunderstand this and you actually keep a separate queue for each >> pid (which would seem to be a problem as you no longer know how much space >> you need) > > You're correct -- that's the model at present. We'd like to move to a > model where we have better control and are kicking around ideas for > how to do this for the next platform version. > > The rate at which apps push data into logs is pretty amazing at times. > The system booting (maybe 10-20 services and 10+ apps starting up) > can blow through 256K of ringbuffer in seconds. > > Having enough context available when something crashes to be able to > diagnose what went wrong, especially when problems could involve > interaction between multiple agents in multiple processes is important > for the frameworks and apps teams.
this makes it sound more like this belongs in userspace instead of the kernel. if something crashes and they can flip a flag in userspace to say 'keep more logs now' and try to duplicate the crash is going to be far easier than having to compile a new kernel to extend the size of the log.
> Trying to get individual developers to be frugal with their logging > has turned out to be mostly a losing battle.
that's for sure, anything that's success depends on developers doing things right that aren't visible to the user are pretty much doomed.
David Lang | |