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Fri, 3 Jul 2020 14:20:16 +0000 (UTC) Date: Fri, 3 Jul 2020 15:20:13 +0100 From: "Dr. David Alan Gilbert" To: Keqian Zhu Subject: Re: [PATCH v3] migration: Count new_dirty instead of real_dirty Message-ID: <20200703142013.GC36813@work-vm> References: <20200622032037.31112-1-zhukeqian1@huawei.com> MIME-Version: 1.0 In-Reply-To: <20200622032037.31112-1-zhukeqian1@huawei.com> User-Agent: Mutt/1.14.5 (2020-06-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/03 03:17:33 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: zhang.zhanghailiang@huawei.com, Juan Quintela , wanghaibin.wang@huawei.com, Chao Fan , qemu-devel@nongnu.org, qemu-arm@nongnu.org, jianjay.zhou@huawei.com, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Keqian Zhu (zhukeqian1@huawei.com) wrote: > real_dirty_pages becomes equal to total ram size after dirty log sync > in ram_init_bitmaps, the reason is that the bitmap of ramblock is > initialized to be all set, so old path counts them as "real dirty" at > beginning. > > This causes wrong dirty rate and false positive throttling. > > Signed-off-by: Keqian Zhu OK, Reviewed-by: Dr. David Alan Gilbert and queued. you might still want to look at migration_trigger_thrtottle and see if you can stop the throttling if in the RAM bulk stage. > --- > Changelog: > > v3: > - Address Dave's comments. > > v2: > - Use new_dirty_pages instead of accu_dirty_pages. > - Adjust commit messages. > --- > include/exec/ram_addr.h | 5 +---- > migration/ram.c | 8 +++++--- > 2 files changed, 6 insertions(+), 7 deletions(-) > > diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h > index 7b5c24e928..3ef729a23c 100644 > --- a/include/exec/ram_addr.h > +++ b/include/exec/ram_addr.h > @@ -442,8 +442,7 @@ static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start, > static inline > uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb, > ram_addr_t start, > - ram_addr_t length, > - uint64_t *real_dirty_pages) > + ram_addr_t length) > { > ram_addr_t addr; > unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS); > @@ -469,7 +468,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb, > if (src[idx][offset]) { > unsigned long bits = atomic_xchg(&src[idx][offset], 0); > unsigned long new_dirty; > - *real_dirty_pages += ctpopl(bits); > new_dirty = ~dest[k]; > dest[k] |= bits; > new_dirty &= bits; > @@ -502,7 +500,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb, > start + addr + offset, > TARGET_PAGE_SIZE, > DIRTY_MEMORY_MIGRATION)) { > - *real_dirty_pages += 1; > long k = (start + addr) >> TARGET_PAGE_BITS; > if (!test_and_set_bit(k, dest)) { > num_dirty++; > diff --git a/migration/ram.c b/migration/ram.c > index 069b6e30bc..5554a7d2d8 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -859,9 +859,11 @@ static inline bool migration_bitmap_clear_dirty(RAMState *rs, > /* Called with RCU critical section */ > static void ramblock_sync_dirty_bitmap(RAMState *rs, RAMBlock *rb) > { > - rs->migration_dirty_pages += > - cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length, > - &rs->num_dirty_pages_period); > + uint64_t new_dirty_pages = > + cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length); > + > + rs->migration_dirty_pages += new_dirty_pages; > + rs->num_dirty_pages_period += new_dirty_pages; > } > > /** > -- > 2.19.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK