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Wed, 26 Aug 2020 12:30:18 +0000 (UTC) Date: Wed, 26 Aug 2020 13:30:16 +0100 From: "Dr. David Alan Gilbert" To: David Edmondson Subject: Re: [PATCH v5 06/12] migration/dirtyrate: Record hash results for each sampled page Message-ID: <20200826123016.GA2727@work-vm> References: <1598260480-64862-1-git-send-email-zhengchuan@huawei.com> <1598260480-64862-7-git-send-email-zhengchuan@huawei.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/26 03:16:15 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=-0.959, 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=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alex.chen@huawei.com, berrange@redhat.com, zhang.zhanghailiang@huawei.com, quintela@redhat.com, qemu-devel@nongnu.org, xiexiangyou@huawei.com, Chuan Zheng , ann.zhuangyanying@huawei.com, fangying1@huawei.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * David Edmondson (dme@dme.org) wrote: > On Monday, 2020-08-24 at 17:14:34 +08, Chuan Zheng wrote: > > > Record hash results for each sampled page, crc32 is taken to calculate > > hash results for each sampled 4K-page. > > > > Signed-off-by: Chuan Zheng > > Signed-off-by: YanYing Zhuang > > --- > > migration/dirtyrate.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++ > > migration/dirtyrate.h | 15 ++++++ > > 2 files changed, 151 insertions(+) > > > > diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c > > index f6a94d8..66de426 100644 > > --- a/migration/dirtyrate.c > > +++ b/migration/dirtyrate.c > > @@ -10,6 +10,7 @@ > > * See the COPYING file in the top-level directory. > > */ > > > > +#include > > #include "qemu/osdep.h" > > #include "qapi/error.h" > > #include "crypto/hash.h" > > @@ -66,6 +67,141 @@ static void update_dirtyrate(uint64_t msec) > > DirtyStat.dirty_rate = dirtyrate; > > } > > > > +/* > > + * get hash result for the sampled memory with length of 4K byte in ramblock, > > + * which starts from ramblock base address. > > + */ > > +static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info, > > + uint64_t vfn) > > +{ > > + struct iovec iov_array; > > There's no need for an iovec now that crc32() is being used. > > > + uint32_t crc; > > + > > + iov_array.iov_base = info->ramblock_addr + > > + vfn * DIRTYRATE_SAMPLE_PAGE_SIZE; > > + iov_array.iov_len = DIRTYRATE_SAMPLE_PAGE_SIZE; > > + > > + crc = crc32(0, iov_array.iov_base, iov_array.iov_len); > > + > > + return crc; > > +} > > + > > +static int save_ramblock_hash(struct RamblockDirtyInfo *info) > > +{ > > + unsigned int sample_pages_count; > > + int i; > > + int ret = -1; > > There's no need to initialise "ret". > > > + GRand *rand = g_rand_new(); > > Calling g_rand_new() when the result may not be used (because of the > various conditions immediately below) seems as though it might waste > entropy. Could this be pushed down just above the loop? It would even > get rid of the gotos ;-) > > > + sample_pages_count = info->sample_pages_count; > > + > > + /* ramblock size less than one page, return success to skip this ramblock */ > > + if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) { > > + ret = 0; > > + goto out; > > + } > > + > > + info->hash_result = g_try_malloc0_n(sample_pages_count, > > + sizeof(uint32_t)); > > + if (!info->hash_result) { > > + ret = -1; > > + goto out; > > + } > > + > > + info->sample_page_vfn = g_try_malloc0_n(sample_pages_count, > > + sizeof(uint64_t)); > > + if (!info->sample_page_vfn) { > > + g_free(info->hash_result); > > + ret = -1; > > + goto out; > > + } > > + > > + for (i = 0; i < sample_pages_count; i++) { > > + info->sample_page_vfn[i] = g_rand_int_range(rand, 0, > > + info->ramblock_pages - 1); > > + info->hash_result[i] = get_ramblock_vfn_hash(info, > > + info->sample_page_vfn[i]); > > + } > > + ret = 0; > > + > > +out: > > + g_rand_free(rand); > > + return ret; > > +} > > + > > +static void get_ramblock_dirty_info(RAMBlock *block, > > + struct RamblockDirtyInfo *info, > > + struct DirtyRateConfig *config) > > +{ > > + uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes; > > + > > + /* Right shift 30 bits to calc block size in GB */ > > + info->sample_pages_count = (qemu_ram_get_used_length(block) * > > + sample_pages_per_gigabytes) >> > > + DIRTYRATE_PAGE_SHIFT_GB; > > Doing the calculation this way around seems odd. Why was it not: > > info->sample_pages_count = (qemu_ram_get_used_length(block) >> > DIRTYRATE_PAGE_SHIFT_GB) * > sample_pages_per_gigabytes; > > ? Because that would give 0 for a 0.5GB block Dave > > + > > + /* Right shift 12 bits to calc page count in 4KB */ > > + info->ramblock_pages = qemu_ram_get_used_length(block) >> > > + DIRTYRATE_PAGE_SHIFT_KB; > > + info->ramblock_addr = qemu_ram_get_host_addr(block); > > + strcpy(info->idstr, qemu_ram_get_idstr(block)); > > +} > > + > > +static struct RamblockDirtyInfo * > > +alloc_ramblock_dirty_info(int *block_index, > > + struct RamblockDirtyInfo *block_dinfo) > > +{ > > + struct RamblockDirtyInfo *info = NULL; > > + int index = *block_index; > > + > > + if (!block_dinfo) { > > + index = 0; > > + block_dinfo = g_try_new(struct RamblockDirtyInfo, 1); > > + } else { > > + index++; > > + block_dinfo = g_try_realloc(block_dinfo, (index + 1) * > > + sizeof(struct RamblockDirtyInfo)); > > g_try_renew() instead of g_try_realloc()? > > > + } > > + if (!block_dinfo) { > > + return NULL; > > + } > > + > > + info = &block_dinfo[index]; > > + *block_index = index; > > + memset(info, 0, sizeof(struct RamblockDirtyInfo)); > > + > > + return block_dinfo; > > +} > > + > > +static int record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo, > > + struct DirtyRateConfig config, > > + int *block_index) > > +{ > > + struct RamblockDirtyInfo *info = NULL; > > + struct RamblockDirtyInfo *dinfo = NULL; > > + RAMBlock *block = NULL; > > There's no need to initialise "info" or "block". > > The declaration of "info" could be pushed into the loop. > > > + int index = 0; > > + > > + RAMBLOCK_FOREACH_MIGRATABLE(block) { > > + dinfo = alloc_ramblock_dirty_info(&index, dinfo); > > + if (dinfo == NULL) { > > + return -1; > > + } > > + info = &dinfo[index]; > > + get_ramblock_dirty_info(block, info, &config); > > + if (save_ramblock_hash(info) < 0) { > > + *block_dinfo = dinfo; > > + *block_index = index; > > + return -1; > > + } > > + } > > + > > + *block_dinfo = dinfo; > > + *block_index = index; > > + > > + return 0; > > +} > > + > > static void calculate_dirtyrate(struct DirtyRateConfig config) > > { > > /* todo */ > > diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h > > index 9db269d..5050add 100644 > > --- a/migration/dirtyrate.h > > +++ b/migration/dirtyrate.h > > @@ -24,6 +24,21 @@ > > */ > > #define RAMBLOCK_INFO_MAX_LEN 256 > > > > +/* > > + * Sample page size 4K as default. > > + */ > > +#define DIRTYRATE_SAMPLE_PAGE_SIZE 4096 > > + > > +/* > > + * Sample page size 4K shift > > + */ > > +#define DIRTYRATE_PAGE_SHIFT_KB 12 > > + > > +/* > > + * Sample page size 1G shift > > + */ > > +#define DIRTYRATE_PAGE_SHIFT_GB 30 > > + > > /* Take 1s as default for calculation duration */ > > #define DEFAULT_FETCH_DIRTYRATE_TIME_SEC 1 > > > > -- > > 1.8.3.1 > > dme. > -- > You bring light in. > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK