reassign 634149 src:linux-2.6 tags 634149 - moreinfo + confirmed merge 633589 634149 thanks
18.07.2011 14:24, Michael Tokarev wrote: [..] So, the problem is that with this kernel commit: commit 7972995b0c346de76fe260ce0fd6bcc8ffab724a Author: Gleb Natapov <[email protected]> Date: Thu Mar 18 15:20:24 2010 +0200 KVM: x86 emulator: Move string pio emulation into emulator.c Currently emulation is done outside of emulator so things like doing ins/outs to/from mmio are broken it also makes it hard (if not impossible) to implement single stepping in the future. The implementation in this patch is not efficient since it exits to userspace for each IO while previous implementation did 'ins' in batches. Further patch that implements pio in string read ahead address this problem. Signed-off-by: Gleb Natapov <[email protected]> Signed-off-by: Marcelo Tosatti <[email protected]> which went into mainline with 2.6.35, there has been quite some changes in PIO emulation handling in kvm which resulted in correct but slow (as opposed by fast but incorrect) emulation. This slowed down guests that use PIO to access disks. Among these are WinXP (it switches from DMA to PIO after some I/O errors), WinNT (ditto) and - apparently - Hurd. Someone needs to investigate why Hurd does not use DMA in this case - PIO is long obsolete technology. I'd mark this as "notabug" (not possible with BTS) or "wontfix", but it's definitely possible to optimize the new code further to speed things up. If it's worth the effort is another question. /mjt -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
