From: Takuya Yoshikawa Date: Wed, 25 May 2011 02:09:38 +0000 (+0900) Subject: KVM: x86 emulator: Avoid clearing the whole decode_cache X-Git-Tag: v3.1-rc1~264^2~125 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b5c9ff731f3cee5a2f2d7154f48f8006b48eb66d;p=pandora-kernel.git KVM: x86 emulator: Avoid clearing the whole decode_cache 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. Signed-off-by: Takuya Yoshikawa Cc: Gleb Natapov Signed-off-by: Avi Kivity --- Reading git-diff-tree failed