From patchwork Tue Nov 15 12:12:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Juan Quintela X-Patchwork-Id: 13043611 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5867CC433FE for ; Tue, 15 Nov 2022 12:22:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ouuof-0004KM-Go; Tue, 15 Nov 2022 07:13:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ouuod-0004H2-St for qemu-devel@nongnu.org; Tue, 15 Nov 2022 07:13:23 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ouuob-0004f8-30 for qemu-devel@nongnu.org; Tue, 15 Nov 2022 07:13:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668514400; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4j3dbCKGLbNDGAn+c9H7VpwArQIYSq5GKQxPanVzcRI=; b=N2ECObxCdOl8cELNSXEDG+/SVsOJ/a6YbEIY9e+JkDnFja9vag77v6FbTmt4WBcjcTrZqC RoCrmSVGDAH1JRyoI1WL14Rc8HYtfuKw1o/LIkFKibSgjt+zqnzVHMumF+iDOR7mHbhyMI 5De8gLDLOCyVR+qtPP3834c/A6rpth4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-373-TH3Esq83OducTiPzAOK7LQ-1; Tue, 15 Nov 2022 07:13:17 -0500 X-MC-Unique: TH3Esq83OducTiPzAOK7LQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E57B83C0DDC0; Tue, 15 Nov 2022 12:13:16 +0000 (UTC) Received: from secure.mitica (unknown [10.39.195.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6521E492B05; Tue, 15 Nov 2022 12:13:14 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Cc: Paolo Bonzini , David Hildenbrand , Laurent Vivier , Stefan Hajnoczi , Fam Zheng , qemu-block@nongnu.org, "Dr. David Alan Gilbert" , Thomas Huth , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , qemu-trivial@nongnu.org, Michael Tokarev , =?utf-8?q?Daniel?= =?utf-8?q?_P=2E_Berrang=C3=A9?= , =?utf-8?q?Marc-Andr?= =?utf-8?q?=C3=A9_Lureau?= , Peter Xu , Juan Quintela Subject: [PATCH 13/30] migration: Use non-atomic ops for clear log bitmap Date: Tue, 15 Nov 2022 13:12:09 +0100 Message-Id: <20221115121226.26609-14-quintela@redhat.com> In-Reply-To: <20221115121226.26609-1-quintela@redhat.com> References: <20221115121226.26609-1-quintela@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.129.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Peter Xu Since we already have bitmap_mutex to protect either the dirty bitmap or the clear log bitmap, we don't need atomic operations to set/clear/test on the clear log bitmap. Switching all ops from atomic to non-atomic versions, meanwhile touch up the comments to show which lock is in charge. Introduced non-atomic version of bitmap_test_and_clear_atomic(), mostly the same as the atomic version but simplified a few places, e.g. dropped the "old_bits" variable, and also the explicit memory barriers. Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- include/exec/ram_addr.h | 11 +++++----- include/exec/ramblock.h | 3 +++ include/qemu/bitmap.h | 1 + util/bitmap.c | 45 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 55 insertions(+), 5 deletions(-) diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index 1500680458..f4fb6a2111 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -42,7 +42,8 @@ static inline long clear_bmap_size(uint64_t pages, uint8_t shift) } /** - * clear_bmap_set: set clear bitmap for the page range + * clear_bmap_set: set clear bitmap for the page range. Must be with + * bitmap_mutex held. * * @rb: the ramblock to operate on * @start: the start page number @@ -55,12 +56,12 @@ static inline void clear_bmap_set(RAMBlock *rb, uint64_t start, { uint8_t shift = rb->clear_bmap_shift; - bitmap_set_atomic(rb->clear_bmap, start >> shift, - clear_bmap_size(npages, shift)); + bitmap_set(rb->clear_bmap, start >> shift, clear_bmap_size(npages, shift)); } /** - * clear_bmap_test_and_clear: test clear bitmap for the page, clear if set + * clear_bmap_test_and_clear: test clear bitmap for the page, clear if set. + * Must be with bitmap_mutex held. * * @rb: the ramblock to operate on * @page: the page number to check @@ -71,7 +72,7 @@ static inline bool clear_bmap_test_and_clear(RAMBlock *rb, uint64_t page) { uint8_t shift = rb->clear_bmap_shift; - return bitmap_test_and_clear_atomic(rb->clear_bmap, page >> shift, 1); + return bitmap_test_and_clear(rb->clear_bmap, page >> shift, 1); } static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset) diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h index 6cbedf9e0c..adc03df59c 100644 --- a/include/exec/ramblock.h +++ b/include/exec/ramblock.h @@ -53,6 +53,9 @@ struct RAMBlock { * and split clearing of dirty bitmap on the remote node (e.g., * KVM). The bitmap will be set only when doing global sync. * + * It is only used during src side of ram migration, and it is + * protected by the global ram_state.bitmap_mutex. + * * NOTE: this bitmap is different comparing to the other bitmaps * in that one bit can represent multiple guest pages (which is * decided by the `clear_bmap_shift' variable below). On diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h index 82a1d2f41f..3ccb00865f 100644 --- a/include/qemu/bitmap.h +++ b/include/qemu/bitmap.h @@ -253,6 +253,7 @@ void bitmap_set(unsigned long *map, long i, long len); void bitmap_set_atomic(unsigned long *map, long i, long len); void bitmap_clear(unsigned long *map, long start, long nr); bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr); +bool bitmap_test_and_clear(unsigned long *map, long start, long nr); void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src, long nr); unsigned long bitmap_find_next_zero_area(unsigned long *map, diff --git a/util/bitmap.c b/util/bitmap.c index f81d8057a7..8d12e90a5a 100644 --- a/util/bitmap.c +++ b/util/bitmap.c @@ -240,6 +240,51 @@ void bitmap_clear(unsigned long *map, long start, long nr) } } +bool bitmap_test_and_clear(unsigned long *map, long start, long nr) +{ + unsigned long *p = map + BIT_WORD(start); + const long size = start + nr; + int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); + unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); + bool dirty = false; + + assert(start >= 0 && nr >= 0); + + /* First word */ + if (nr - bits_to_clear > 0) { + if ((*p) & mask_to_clear) { + dirty = true; + } + *p &= ~mask_to_clear; + nr -= bits_to_clear; + bits_to_clear = BITS_PER_LONG; + p++; + } + + /* Full words */ + if (bits_to_clear == BITS_PER_LONG) { + while (nr >= BITS_PER_LONG) { + if (*p) { + dirty = true; + *p = 0; + } + nr -= BITS_PER_LONG; + p++; + } + } + + /* Last word */ + if (nr) { + mask_to_clear &= BITMAP_LAST_WORD_MASK(size); + if ((*p) & mask_to_clear) { + dirty = true; + } + *p &= ~mask_to_clear; + } + + return dirty; +} + bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr) { unsigned long *p = map + BIT_WORD(start);