On 11/06/2012 05:49 PM, Dave Jones wrote:
On Tue, Nov 06, 2012 at 05:24:15PM -0600, Nathan Zimmer wrote: > On Tue, Nov 06, 2012 at 04:31:28PM -0500, Dave Jones wrote: > > On Tue, Nov 06, 2012 at 03:02:21PM -0600, Nathan Zimmer wrote: > > > On systems with 4096 cores attemping to read /proc/sched_debug fails. > > > We are trying to push all the data into a single kmalloc buffer. > > > The issue is on these very large machines all the data will not fit in 4mb. > > > > > > A better solution is to not us the single_open mechanism but to provide > > > our own seq_operations and treat each cpu as an individual record. > > > > Good timing. > > > > This looks like it would solve the problem I just reported here: > > https://lkml.org/lkml/2012/11/6/390 > > > > That happens even on an 8-way, so it's not just niche machines that have > > this problems. > > Glad to help. I hadn't thought of memory tight situation but it does make sense > that it helps as it can get by with 4k allocation vs grabbing successively > large chucks. > > If you have seen similar issues with your fuzz testing let me know where and > I'll take a look.I think /proc/timer_list could probably use the same treatment. I had traces showing that using 64k allocations too, but I think I may have just bricked my testbox. Dave
Yup it looks like /proc/timer_list is doing the thing with single open. nzimmer@harp50-sys:~> cat /proc/timer_list cat: /proc/timer_list: Cannot allocate memory nzimmer@harp50-sys:~> I'll see if I can squeeze that one in too. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
