On Wed, Jan 2, 2013 at 2:39 PM, Andrew Morton <a...@linux-foundation.org> wrote: > On Sun, 30 Dec 2012 18:47:12 -0800 > Michel Lespinasse <wal...@google.com> wrote: > >> I'm not sure whats' the back story with synchro-test though - they seem >> to have been stuck in andrew's tree for a very long time now. Is there >> any reason delaying their inclusion or is it just that nobody's been >> pushing for them ? > > iirc, we decided that synchro-test wasn't valuable/important enough to > put into mainline. So it has been living in -mm for, umm, seven years. > > Let's revisit that decision. What do you think is the case for inclusion?
Sorry for the late reply. I agree that this isn't useful on an everyday basis, however such a test could be useful whenever some locking discussions come up, such as with the spinlock performance discussions when I started this thread, or the rwsem write lock stealing right now. Also, I think we've accepted a lot more non-core-kernel things over the last 7 years, so the bar may be lower now. > Here it is. It will need a full re-review. I think the first thing we may want to do is ask David if he has an updated version - if he's been making changes, it would be rude to him to check in a 7 year old version of his code. > From: David Howells <dhowe...@redhat.com> > Subject: mutex subsystem, synchro-test module > > The attached patch adds a module for testing and benchmarking mutexes, > semaphores and R/W semaphores. > > Using it is simple: > > insmod synchro-test.ko <args> > > It will exit with error ENOANO after running the tests and printing the > results to the kernel console log. > > The available arguments are: > > (*) mx=N > > Start up to N mutex thrashing threads, where N is at most 20. All will > try and thrash the same mutex. Actually N is at most 64 > (*) sm=N > > Start up to N counting semaphore thrashing threads, where N is at most > 20. All will try and thrash the same semaphore. N is at most 64 > (*) ism=M > > Initialise the counting semaphore with M, where M is any positive > integer greater than zero. The default is 4. > > (*) rd=N > (*) wr=O > (*) dg=P > > Start up to N reader thrashing threads, O writer thrashing threads and > P downgrader thrashing threads, where N, O and P are at most 20 > apiece. All will try and thrash the same read/write semaphore. N, O and P are at most 64 > (*) elapse=N > > Run the tests for N seconds. The default is 5. > > (*) load=N > > Each thread delays for N uS whilst holding the lock. The dfault is 0. default is 2 (I had actually sent a change to correct the doc here) > (*) interval=N > > Each thread delays for N uS whilst not holding the lock. The default > is 0. default is 2 (I had actually sent a change to correct the doc here) > (*) do_sched=1 > > Each thread will call schedule if required after each iteration. > > (*) v=1 > > Print more verbose information, including a thread iteration > distribution list. > > The module should be enabled by turning on CONFIG_DEBUG_SYNCHRO_TEST to "m". > > [randy.dun...@oracle.com: fix build errors, add <sched.h> header file] > [a...@linux-foundation.org: remove smp_lock.h inclusion] > [v...@zeniv.linux.org.uk: kill daemonize() calls] > [rdun...@xenotime.net: fix printk format warrnings] > [wal...@google.com: add spinlock test] > [wal...@google.com: document default load and interval values] > Signed-off-by: David Howells <dhowe...@redhat.com> > Signed-off-by: Ingo Molnar <mi...@elte.hu> > Signed-off-by: Adrian Bunk <b...@stusta.de> > Signed-off-by: Randy Dunlap <rdun...@xenotime.net> > Signed-off-by: Michel Lespinasse <wal...@google.com> > Signed-off-by: Andrew Morton <a...@linux-foundation.org> > --- > > Documentation/synchro-test.txt | 59 +++ > kernel/Makefile | 1 > kernel/synchro-test.c | 586 +++++++++++++++++++++++++++++++ > lib/Kconfig.debug | 14 > 4 files changed, 660 insertions(+) It's unclear if synchro-test.c should be in kernel/ - I think similar tests nowadays tend to be in lib/ instead, though not always :) > diff -puN /dev/null Documentation/synchro-test.txt > --- /dev/null > +++ a/Documentation/synchro-test.txt > @@ -0,0 +1,59 @@ > +The synchro-test.ko module can be used for testing and benchmarking mutexes, > +semaphores and R/W semaphores. > + > +The module is compiled by setting CONFIG_DEBUG_SYNCHRO_TEST to "m" when > +configuring the kernel. > + > +Using it is simple: > + > + insmod synchro-test.ko <args> > + > +It will exit with error ENOANO after running the tests and printing the > +results to the kernel console log. > + > +The available arguments are: > + > + (*) mx=N > + > + Start up to N mutex thrashing threads, where N is at most 20. All will > + try and thrash the same mutex. max 64 > + (*) sm=N > + > + Start up to N counting semaphore thrashing threads, where N is at most > + 20. All will try and thrash the same semaphore. max 64 > + (*) ism=M > + > + Initialise the counting semaphore with M, where M is any positive > + integer greater than zero. The default is 4. > + > + (*) rd=N > + (*) wr=O > + (*) dg=P > + > + Start up to N reader thrashing threads, O writer thrashing threads and > + P downgrader thrashing threads, where N, O and P are at most 20 > + apiece. All will try and thrash the same read/write semaphore. max 64 > + (*) elapse=N > + > + Run the tests for N seconds. The default is 5. > + > + (*) load=N > + > + Each thread delays for N uS whilst holding the lock. The default is 2. > + > + (*) interval=N > + > + Each thread delays for N uS whilst not holding the lock. The default > + is 2. > + > + (*) do_sched=1 > + > + Each thread will call schedule if required after each iteration. > + > + (*) v=1 > + > + Print more verbose information, including a thread iteration > + distribution list. Other than that I'm happy enough with the rest of this code :) -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
