On Thu, Sep 1, 2011 at 9:14 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > On Fri, 26 Aug 2011, John Kacur wrote: > >> Problem: >> make O=/bld/3.0.3-rt11/ kernel/fork.o >> /home/jkacur/jk-2.6/kernel/fork.c:91: error: section of ‘name’ conflicts with previous declaration >> >> __cacheline_aligned is already part of the definition of DEFINE_RWLOCK >> for -rt >> >> However it is not always used for the tasklist_lock in non-rt, so it can't >> simply be added to the definition of DEFINE_RWLOCK in non-rt, so I modified >> the definition in fork.c > > -ENOPARSE > > The real question is whether RWLOCKS should be cacheline aligned in > general or the RT addon is just overkill. Slapping an ifdef around > does not answer that. > Right, this was just a "put out a build-break fire" for now patch and not a good long term patch. I noticed that of all the mainline DEFINE_RWLOCKs that only the tasklist_lock is cache aligned. I'm wondering if there is a reason for that, or just more of a historical accident. Regarding cache aligning the rwlocks in -rt, I also can't find the historical reason for it, do you remember if it was for latency performance, or did we have a atomicity issue on some architectures when we didn't cache align it? Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
