From patchwork Mon Aug 6 17:51:23 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Orit Wasserman X-Patchwork-Id: 175424 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id BD7172C0082 for ; Tue, 7 Aug 2012 04:44:29 +1000 (EST) Received: from localhost ([::1]:60650 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SySFS-0004Do-9G for incoming@patchwork.ozlabs.org; Mon, 06 Aug 2012 14:41:50 -0400 Received: from eggs.gnu.org ([208.118.235.92]:33555) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SySES-0001iL-Ty for qemu-devel@nongnu.org; Mon, 06 Aug 2012 14:40:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SySER-00025y-JG for qemu-devel@nongnu.org; Mon, 06 Aug 2012 14:40:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64199) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SySER-000255-Am for qemu-devel@nongnu.org; Mon, 06 Aug 2012 14:40:47 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q76Idqn2017871 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 6 Aug 2012 14:40:40 -0400 Received: from dhcp-1-120.tlv.redhat.com (vpn-202-8.tlv.redhat.com [10.35.202.8]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id q76HpKII029003; Mon, 6 Aug 2012 13:51:56 -0400 From: Orit Wasserman To: qemu-devel@nongnu.org Date: Mon, 6 Aug 2012 20:51:23 +0300 Message-Id: <1344275489-28789-7-git-send-email-owasserm@redhat.com> In-Reply-To: <1344275489-28789-1-git-send-email-owasserm@redhat.com> References: <1344275489-28789-1-git-send-email-owasserm@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.132.183.28 Cc: peter.maydell@linaro.org, aliguori@us.ibm.com, quintela@redhat.com, Petter Svard , stefanha@gmail.com, mdroth@linux.vnet.ibm.com, Benoit Hudzia , lcapitulino@redhat.com, blauwirbel@gmail.com, Orit Wasserman , chegu_vinod@hp.com, avi@redhat.com, Aidan Shribman , pbonzini@redhat.com, eblake@redhat.com Subject: [Qemu-devel] [PATCH 06/12] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org For performance we are encoding long word at a time. For nzrun we use long-word-at-a-time NULL-detection tricks from strcmp(): using ((lword - 0x0101010101010101) & (~lword) & 0x8080808080808080) test to find out if any byte in the long word is zero. Signed-off-by: Benoit Hudzia Signed-off-by: Petter Svard Signed-off-by: Aidan Shribman Signed-off-by: Orit Wasserman Signed-off-by: Eric Blake --- migration.h | 4 ++ savevm.c | 159 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 163 insertions(+), 0 deletions(-) diff --git a/migration.h b/migration.h index 713aae0..743c366 100644 --- a/migration.h +++ b/migration.h @@ -100,4 +100,8 @@ void migrate_add_blocker(Error *reason); */ void migrate_del_blocker(Error *reason); +int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen, + uint8_t *dst, int dlen); +int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen); + #endif diff --git a/savevm.c b/savevm.c index 6e82b2d..0ea10c9 100644 --- a/savevm.c +++ b/savevm.c @@ -2392,3 +2392,162 @@ void vmstate_register_ram_global(MemoryRegion *mr) { vmstate_register_ram(mr, NULL); } + +/* + page = zrun nzrun + | zrun nzrun page + + zrun = length + + nzrun = length byte... + + length = uleb128 encoded integer + */ +int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen, + uint8_t *dst, int dlen) +{ + uint32_t zrun_len = 0, nzrun_len = 0; + int d = 0, i = 0; + long res, xor; + uint8_t *nzrun_start = NULL; + + g_assert(!(((uintptr_t)old_buf | (uintptr_t)new_buf | slen) % + sizeof(long))); + + while (i < slen) { + /* overflow */ + if (d + 2 > dlen) { + return -1; + } + + /* not aligned to sizeof(long) */ + res = (slen - i) % sizeof(long); + while (res && old_buf[i] == new_buf[i]) { + zrun_len++; + i++; + res--; + } + + /* word at a time for speed */ + if (!res) { + while (i < slen && + (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) { + i += sizeof(long); + zrun_len += sizeof(long); + } + + /* go over the rest */ + while (i < slen && old_buf[i] == new_buf[i]) { + zrun_len++; + i++; + } + } + + /* buffer unchanged */ + if (zrun_len == slen) { + return 0; + } + + /* skip last zero run */ + if (i == slen) { + return d; + } + + d += uleb128_encode_small(dst + d, zrun_len); + + zrun_len = 0; + nzrun_start = new_buf + i; + + /* overflow */ + if (d + 2 > dlen) { + return -1; + } + /* not aligned to sizeof(long) */ + res = (slen - i) % sizeof(long); + while (res && old_buf[i] != new_buf[i]) { + i++; + nzrun_len++; + res--; + } + + /* word at a time for speed, use of 32-bit long okay */ + if (!res) { + /* truncation to 32-bit long okay */ + long mask = 0x0101010101010101ULL; + while (i < slen) { + xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i); + if ((xor - mask) & ~xor & (mask << 7)) { + /* found the end of an nzrun within the current long */ + while (old_buf[i] != new_buf[i]) { + nzrun_len++; + i++; + } + break; + } else { + i += sizeof(long); + nzrun_len += sizeof(long); + } + } + } + + d += uleb128_encode_small(dst + d, nzrun_len); + /* overflow */ + if (d + nzrun_len > dlen) { + return -1; + } + memcpy(dst + d, nzrun_start, nzrun_len); + d += nzrun_len; + nzrun_len = 0; + } + + return d; +} + +int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen) +{ + int i = 0, d = 0; + int ret; + uint32_t count = 0; + + while (i < slen) { + + /* zrun */ + if ((slen - i) < 2) { + return -1; + } + + ret = uleb128_decode_small(src + i, &count); + if (ret < 0 || (i && !count)) { + return -1; + } + i += ret; + d += count; + + /* overflow */ + if (d > dlen) { + return -1; + } + + /* nzrun */ + if ((slen - i) < 2) { + return -1; + } + + ret = uleb128_decode_small(src + i, &count); + if (ret < 0 || !count) { + return -1; + } + i += ret; + + /* overflow */ + if (d + count > dlen || i + count > slen) { + return -1; + } + + memcpy(dst + d, src + i, count); + d += count; + i += count; + } + + return d; +}