From patchwork Fri Jun 17 13:06:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amit Shah X-Patchwork-Id: 637020 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3rWLVv5qndz9t2F for ; Fri, 17 Jun 2016 23:21:27 +1000 (AEST) Received: from localhost ([::1]:57443 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDti9-0006ci-H4 for incoming@patchwork.ozlabs.org; Fri, 17 Jun 2016 09:21:25 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56029) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDtUk-0007jD-M8 for qemu-devel@nongnu.org; Fri, 17 Jun 2016 09:07:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bDtUe-000887-Fp for qemu-devel@nongnu.org; Fri, 17 Jun 2016 09:07:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52566) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDtUe-00087w-7d for qemu-devel@nongnu.org; Fri, 17 Jun 2016 09:07:28 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DD0B5C057EC9; Fri, 17 Jun 2016 13:07:27 +0000 (UTC) Received: from localhost (ovpn-116-17.sin2.redhat.com [10.67.116.17]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u5HD7Ph8014342; Fri, 17 Jun 2016 09:07:26 -0400 From: Amit Shah To: Peter Maydell Date: Fri, 17 Jun 2016 18:36:49 +0530 Message-Id: In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 17 Jun 2016 13:07:27 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 10/13] migration: refine the compression code X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , liang.z.li@intel.com, qemu list , "Dr. David Alan Gilbert" , Amit Shah , den@openvz.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Liang Li The current code for multi-thread compression is not clear, especially in the aspect of using lock. Refine the code to make it clear. Signed-off-by: Liang Li Message-Id: <1462433579-13691-8-git-send-email-liang.z.li@intel.com> Signed-off-by: Amit Shah --- migration/ram.c | 84 +++++++++++++++++++++++++++------------------------------ 1 file changed, 40 insertions(+), 44 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index a5ed21b..59473d9 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -253,7 +253,6 @@ static struct BitmapRcu { } *migration_bitmap_rcu; struct CompressParam { - bool start; bool done; bool quit; QEMUFile *file; @@ -293,34 +292,36 @@ static QemuThread *decompress_threads; static QemuMutex decomp_done_lock; static QemuCond decomp_done_cond; -static int do_compress_ram_page(CompressParam *param); +static int do_compress_ram_page(QEMUFile *f, RAMBlock *block, + ram_addr_t offset); static void *do_data_compress(void *opaque) { CompressParam *param = opaque; + RAMBlock *block; + ram_addr_t offset; + qemu_mutex_lock(¶m->mutex); while (!param->quit) { - qemu_mutex_lock(¶m->mutex); - /* Re-check the quit flag in case of - * terminate_compression_threads is called just before - * qemu_mutex_lock(¶m->mutex) and after - * while(!param->quit), re-check it here can make - * sure the compression thread terminate as expected. - */ - while (!param->start && !param->quit) { + if (param->block) { + block = param->block; + offset = param->offset; + param->block = NULL; + qemu_mutex_unlock(¶m->mutex); + + do_compress_ram_page(param->file, block, offset); + + qemu_mutex_lock(comp_done_lock); + param->done = true; + qemu_cond_signal(comp_done_cond); + qemu_mutex_unlock(comp_done_lock); + + qemu_mutex_lock(¶m->mutex); + } else { qemu_cond_wait(¶m->cond, ¶m->mutex); } - if (!param->quit) { - do_compress_ram_page(param); - } - param->start = false; - qemu_mutex_unlock(¶m->mutex); - - qemu_mutex_lock(comp_done_lock); - param->done = true; - qemu_cond_signal(comp_done_cond); - qemu_mutex_unlock(comp_done_lock); } + qemu_mutex_unlock(¶m->mutex); return NULL; } @@ -808,18 +809,15 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus *pss, return pages; } -static int do_compress_ram_page(CompressParam *param) +static int do_compress_ram_page(QEMUFile *f, RAMBlock *block, + ram_addr_t offset) { int bytes_sent, blen; - uint8_t *p; - RAMBlock *block = param->block; - ram_addr_t offset = param->offset; + uint8_t *p = block->host + (offset & TARGET_PAGE_MASK); - p = block->host + (offset & TARGET_PAGE_MASK); - - bytes_sent = save_page_header(param->file, block, offset | + bytes_sent = save_page_header(f, block, offset | RAM_SAVE_FLAG_COMPRESS_PAGE); - blen = qemu_put_compression_data(param->file, p, TARGET_PAGE_SIZE, + blen = qemu_put_compression_data(f, p, TARGET_PAGE_SIZE, migrate_compress_level()); if (blen < 0) { bytes_sent = 0; @@ -832,15 +830,6 @@ static int do_compress_ram_page(CompressParam *param) return bytes_sent; } -static inline void start_compression(CompressParam *param) -{ - param->done = false; - qemu_mutex_lock(¶m->mutex); - param->start = true; - qemu_cond_signal(¶m->cond); - qemu_mutex_unlock(¶m->mutex); -} - static inline void start_decompression(DecompressParam *param) { param->done = false; @@ -860,18 +849,22 @@ static void flush_compressed_data(QEMUFile *f) return; } thread_count = migrate_compress_threads(); + + qemu_mutex_lock(comp_done_lock); for (idx = 0; idx < thread_count; idx++) { - if (!comp_param[idx].done) { - qemu_mutex_lock(comp_done_lock); - while (!comp_param[idx].done && !comp_param[idx].quit) { - qemu_cond_wait(comp_done_cond, comp_done_lock); - } - qemu_mutex_unlock(comp_done_lock); + while (!comp_param[idx].done) { + qemu_cond_wait(comp_done_cond, comp_done_lock); } + } + qemu_mutex_unlock(comp_done_lock); + + for (idx = 0; idx < thread_count; idx++) { + qemu_mutex_lock(&comp_param[idx].mutex); if (!comp_param[idx].quit) { len = qemu_put_qemu_file(f, comp_param[idx].file); bytes_transferred += len; } + qemu_mutex_unlock(&comp_param[idx].mutex); } } @@ -893,9 +886,12 @@ static int compress_page_with_multi_thread(QEMUFile *f, RAMBlock *block, while (true) { for (idx = 0; idx < thread_count; idx++) { if (comp_param[idx].done) { + comp_param[idx].done = false; bytes_xmit = qemu_put_qemu_file(f, comp_param[idx].file); + qemu_mutex_lock(&comp_param[idx].mutex); set_compress_params(&comp_param[idx], block, offset); - start_compression(&comp_param[idx]); + qemu_cond_signal(&comp_param[idx].cond); + qemu_mutex_unlock(&comp_param[idx].mutex); pages = 1; acct_info.norm_pages++; *bytes_transferred += bytes_xmit;