From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AC07AC433C1 for ; Mon, 22 Mar 2021 10:51:14 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 10467619A0 for ; Mon, 22 Mar 2021 10:51:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 10467619A0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:49008 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lOI9Q-0001VU-Ty for qemu-devel@archiver.kernel.org; Mon, 22 Mar 2021 06:51:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38950) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lOI6Z-0007Ur-DF for qemu-devel@nongnu.org; Mon, 22 Mar 2021 06:48:15 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:4395) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lOI6U-0000Te-Bm for qemu-devel@nongnu.org; Mon, 22 Mar 2021 06:48:15 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4F3rl00wBRz1BFLS; Mon, 22 Mar 2021 18:46:04 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.498.0; Mon, 22 Mar 2021 18:47:58 +0800 Subject: Re: [PATCH v5 02/10] KVM: Use a big lock to replace per-kml slots_lock To: Peter Xu , References: <20210310203301.194842-1-peterx@redhat.com> <20210310203301.194842-3-peterx@redhat.com> From: Keqian Zhu Message-ID: <71e85a52-7385-e88a-f51f-9371bc371d06@huawei.com> Date: Mon, 22 Mar 2021 18:47:58 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210310203301.194842-3-peterx@redhat.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.190; envelope-from=zhukeqian1@huawei.com; helo=szxga04-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , Hyman , "Dr . David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Peter, On 2021/3/11 4:32, Peter Xu wrote: > Per-kml slots_lock will bring some trouble if we want to take all slots_lock of > all the KMLs, especially when we're in a context that we could have taken some > of the KML slots_lock, then we even need to figure out what we've taken and > what we need to take. > > Make this simple by merging all KML slots_lock into a single slots lock. > > Per-kml slots_lock isn't anything that helpful anyway - so far only x86 has two > address spaces (so, two slots_locks). All the rest archs will be having one > address space always, which means there's actually one slots_lock so it will be > the same as before. > > Signed-off-by: Peter Xu > --- > accel/kvm/kvm-all.c | 32 +++++++++++++++++--------------- > include/sysemu/kvm_int.h | 2 -- > 2 files changed, 17 insertions(+), 17 deletions(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index f88a52393fe..94e881f123b 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -174,8 +174,10 @@ typedef struct KVMResampleFd KVMResampleFd; > static QLIST_HEAD(, KVMResampleFd) kvm_resample_fd_list = > QLIST_HEAD_INITIALIZER(kvm_resample_fd_list); > > -#define kvm_slots_lock(kml) qemu_mutex_lock(&(kml)->slots_lock) > -#define kvm_slots_unlock(kml) qemu_mutex_unlock(&(kml)->slots_lock) > +static QemuMutex kml_slots_lock; > + > +#define kvm_slots_lock() qemu_mutex_lock(&kml_slots_lock) > +#define kvm_slots_unlock() qemu_mutex_unlock(&kml_slots_lock) nit: qemu_mutex_lock and qemu_mutex_unlock is not aligned. > > static inline void kvm_resample_fd_remove(int gsi) > { > @@ -241,9 +243,9 @@ bool kvm_has_free_slot(MachineState *ms) > bool result; > KVMMemoryListener *kml = &s->memory_listener; > > - kvm_slots_lock(kml); > + kvm_slots_lock(); > result = !!kvm_get_free_slot(kml); > - kvm_slots_unlock(kml); > + kvm_slots_unlock(); > > return result; > } > @@ -309,7 +311,7 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram, > KVMMemoryListener *kml = &s->memory_listener; > int i, ret = 0; > > - kvm_slots_lock(kml); > + kvm_slots_lock(); > for (i = 0; i < s->nr_slots; i++) { > KVMSlot *mem = &kml->slots[i]; > > @@ -319,7 +321,7 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram, > break; > } > } > - kvm_slots_unlock(kml); > + kvm_slots_unlock(); > > return ret; > } > @@ -515,7 +517,7 @@ static int kvm_section_update_flags(KVMMemoryListener *kml, > return 0; > } > > - kvm_slots_lock(kml); > + kvm_slots_lock(); > > while (size && !ret) { > slot_size = MIN(kvm_max_slot_size, size); > @@ -531,7 +533,7 @@ static int kvm_section_update_flags(KVMMemoryListener *kml, > } > > out: > - kvm_slots_unlock(kml); > + kvm_slots_unlock(); > return ret; > } > > @@ -819,7 +821,7 @@ static int kvm_physical_log_clear(KVMMemoryListener *kml, > return ret; > } > > - kvm_slots_lock(kml); > + kvm_slots_lock(); > > for (i = 0; i < s->nr_slots; i++) { > mem = &kml->slots[i]; > @@ -845,7 +847,7 @@ static int kvm_physical_log_clear(KVMMemoryListener *kml, > } > } > > - kvm_slots_unlock(kml); > + kvm_slots_unlock(); > > return ret; > } > @@ -1150,7 +1152,7 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml, > ram = memory_region_get_ram_ptr(mr) + section->offset_within_region + > (start_addr - section->offset_within_address_space); > > - kvm_slots_lock(kml); > + kvm_slots_lock(); > > if (!add) { > do { > @@ -1208,7 +1210,7 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml, > } while (size); > > out: > - kvm_slots_unlock(kml); > + kvm_slots_unlock(); > } > > static void kvm_region_add(MemoryListener *listener, > @@ -1235,9 +1237,9 @@ static void kvm_log_sync(MemoryListener *listener, > KVMMemoryListener *kml = container_of(listener, KVMMemoryListener, listener); > int r; > > - kvm_slots_lock(kml); > + kvm_slots_lock(); > r = kvm_physical_sync_dirty_bitmap(kml, section); > - kvm_slots_unlock(kml); > + kvm_slots_unlock(); > if (r < 0) { > abort(); > } > @@ -1337,7 +1339,7 @@ void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml, > { > int i; > > - qemu_mutex_init(&kml->slots_lock); > + qemu_mutex_init(&kml_slots_lock); As you said, x86 has two address spaces, is it a problem that we may have multi initialization for kml_slots_lock? Thanks, Keqian > kml->slots = g_malloc0(s->nr_slots * sizeof(KVMSlot)); > kml->as_id = as_id; > > diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h > index ccb8869f01b..1da30e18841 100644 > --- a/include/sysemu/kvm_int.h > +++ b/include/sysemu/kvm_int.h > @@ -27,8 +27,6 @@ typedef struct KVMSlot > > typedef struct KVMMemoryListener { > MemoryListener listener; > - /* Protects the slots and all inside them */ > - QemuMutex slots_lock; > KVMSlot *slots; > int as_id; > } KVMMemoryListener; >