Yeap RT has made BKL preemptible. In RT BKL is mutex[sort of counting mutex] instead of spinlock. See my inline response to your query. On Wed, Sep 29, 2010 at 8:11 AM, Tony Poppleton <tony.poppleton@xxxxxxxxx> wrote: > Hi, > > I have read that with each new kernel release, the Big Kernel Lock > (BKL) is gradually being removed from the core kernel code. > > Just out of interest, I was wondering if this has an impact on the RT patch? > > In particular, > - does the RT patch have any connection with the BKL? [MANI:Yes] > - presumably the BKL removal will reduce the average latency of the > unpatched kernel? [MANI: I don't think it is that straight forward. You can avoid BKL in some cases. For eg, you can use unlocked_ioctl instead of ioctl] > - is the BKL currently a source of considerable latency? [MANI: Yes, but I dont have any stats to prove it though] > - will the BKL removal make the RT patch coniderably smaller/simpler? [MANI: Like I said RT just made BKL a mutex] > - has the RT patch effectively been removing the BKL since day 1, or > does it just make the BKL a pre-emptible lock? > > Many thanks, > Tony > -- > 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 > -- Thanks, Manik Think twice about a tree before you take a printout -- 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
