On Thu, May 26, 2011 at 11:19:03AM +0300, Avi Kivity wrote: > On 05/25/2011 05:09 AM, Takuya Yoshikawa wrote: > >From: Takuya Yoshikawa<yoshikawa.takuya@xxxxxxxxxxxxx> > > > >During tracing the emulator, we noticed that init_emulate_ctxt() > >sometimes took a bit longer time than we expected. > > > >This patch is for mitigating the problem by some degree. > > > >By looking into the function, we soon notice that it clears the whole > >decode_cache whose size is about 2.5K bytes now. Furthermore, most of > >the bytes are taken for the two read_cache arrays, which are used only > >by a few instructions. > > > >Considering the fact that we are not assuming the cache arrays have > >been cleared when we store actual data, we do not need to clear the > >arrays: 2K bytes elimination. In addition, we can avoid clearing the > >fetch_cache and regs arrays. > > > >This patch changes the initialization not to clear the arrays. > > > >On our 64-bit host, init_emulate_ctxt() becomes 0.3 to 0.5us faster with > >this patch applied. > > > > Thanks, applied. > > It strikes me that initializing the emulator in x86.c is the wrong > thing. We should move the entire thing to x86_decode_insn(). > We initialize it in task switch and interrupt injection code too. > We'll need a few more callbacks for that, though (register, eflags); > eventually we can read just registers that are used and write only > registers that were updated. > -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
