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 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 4B2E3C47089 for ; Mon, 5 Dec 2022 10:12:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1p28F7-0006OB-Bu; Mon, 05 Dec 2022 04:58:33 -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 1p28F5-0006KF-1O for qemu-devel@nongnu.org; Mon, 05 Dec 2022 04:58:31 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1p28F3-000875-96 for qemu-devel@nongnu.org; Mon, 05 Dec 2022 04:58:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670234308; 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=T/JPm5m9WNX1+QtcngXEAxrLV4M1X8iY9tKJjlFSJj4=; b=WikmF780O2K3IGF1HT5D2Op8LqpAU5F30sEP4aNH88FajMPqhnNaI80ns8Zhb1z9OREtge iyPNhWHYF9AoCUPwVMWP1VvhHS9MCHw3j10NdJbuMOJTUlQ8Ikf1JY4/ulaJRyRkfeaVA9 GmvFzA5YjDDRWj6jiVacZbDMPMP71b0= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-66-3Cx1-7IdMOCZwAvKEwaYDw-1; Mon, 05 Dec 2022 04:58:25 -0500 X-MC-Unique: 3Cx1-7IdMOCZwAvKEwaYDw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 891CA85A588; Mon, 5 Dec 2022 09:58:24 +0000 (UTC) Received: from secure.mitica (unknown [10.39.194.135]) by smtp.corp.redhat.com (Postfix) with ESMTP id 19A942166B29; Mon, 5 Dec 2022 09:58:16 +0000 (UTC) From: Juan Quintela To: qemu-devel@nongnu.org Cc: Fam Zheng , Thomas Huth , Viresh Kumar , Kevin Wolf , Mathieu Poirier , Laurent Vivier , Eric Blake , Richard Henderson , Raphael Norwitz , Stefan Hajnoczi , Juan Quintela , virtio-fs@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Christian Borntraeger , "Gonglei (Arei)" , qemu-block@nongnu.org, Xiaojuan Yang , Thomas Huth , Ilya Leoshkevich , Eduardo Habkost , Gerd Hoffmann , "Dr. David Alan Gilbert" , Alex Williamson , Eric Farman , Halil Pasic , Peter Maydell , Vladimir Sementsov-Ogievskiy , Jason Wang , Laurent Vivier , Song Gao , qemu-s390x@nongnu.org, Pavel Dovgalyuk , Klaus Jensen , John Snow , Michael Tokarev , qemu-arm@nongnu.org, Paolo Bonzini , "Michael S. Tsirkin" , Keith Busch , David Hildenbrand , qemu-trivial@nongnu.org, Hanna Reitz , Peter Xu Subject: [PATCH v2 44/51] migration: Send requested page directly in rp-return thread Date: Mon, 5 Dec 2022 10:52:21 +0100 Message-Id: <20221205095228.1314-45-quintela@redhat.com> In-Reply-To: <20221205095228.1314-1-quintela@redhat.com> References: <20221205095228.1314-1-quintela@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 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, URG_BIZ=0.573 autolearn=no 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 With all the facilities ready, send the requested page directly in the rp-return thread rather than queuing it in the request queue, if and only if postcopy preempt is enabled. It can achieve so because it uses separate channel for sending urgent pages. The only shared data is bitmap and it's protected by the bitmap_mutex. Note that since we're moving the ownership of the urgent channel from the migration thread to rp thread it also means the rp thread is responsible for managing the qemufile, e.g. properly close it when pausing migration happens. For this, let migration_release_from_dst_file to cover shutdown of the urgent channel too, renaming it as migration_release_dst_files() to better show what it does. Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/migration.c | 35 +++++++------ migration/ram.c | 112 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 131 insertions(+), 16 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index de83c50f51..c1d4d76d0c 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2848,8 +2848,11 @@ static int migrate_handle_rp_resume_ack(MigrationState *s, uint32_t value) return 0; } -/* Release ms->rp_state.from_dst_file in a safe way */ -static void migration_release_from_dst_file(MigrationState *ms) +/* + * Release ms->rp_state.from_dst_file (and postcopy_qemufile_src if + * existed) in a safe way. + */ +static void migration_release_dst_files(MigrationState *ms) { QEMUFile *file; @@ -2862,6 +2865,18 @@ static void migration_release_from_dst_file(MigrationState *ms) ms->rp_state.from_dst_file = NULL; } + /* + * Do the same to postcopy fast path socket too if there is. No + * locking needed because this qemufile should only be managed by + * return path thread. + */ + if (ms->postcopy_qemufile_src) { + migration_ioc_unregister_yank_from_file(ms->postcopy_qemufile_src); + qemu_file_shutdown(ms->postcopy_qemufile_src); + qemu_fclose(ms->postcopy_qemufile_src); + ms->postcopy_qemufile_src = NULL; + } + qemu_fclose(file); } @@ -3006,7 +3021,7 @@ out: * Maybe there is something we can do: it looks like a * network down issue, and we pause for a recovery. */ - migration_release_from_dst_file(ms); + migration_release_dst_files(ms); rp = NULL; if (postcopy_pause_return_path_thread(ms)) { /* @@ -3024,7 +3039,7 @@ out: } trace_source_return_path_thread_end(); - migration_release_from_dst_file(ms); + migration_release_dst_files(ms); rcu_unregister_thread(); return NULL; } @@ -3547,18 +3562,6 @@ static MigThrError postcopy_pause(MigrationState *s) qemu_file_shutdown(file); qemu_fclose(file); - /* - * Do the same to postcopy fast path socket too if there is. No - * locking needed because no racer as long as we do this before setting - * status to paused. - */ - if (s->postcopy_qemufile_src) { - migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src); - qemu_file_shutdown(s->postcopy_qemufile_src); - qemu_fclose(s->postcopy_qemufile_src); - s->postcopy_qemufile_src = NULL; - } - migrate_set_state(&s->state, s->state, MIGRATION_STATUS_POSTCOPY_PAUSED); diff --git a/migration/ram.c b/migration/ram.c index 1233ff53ac..16ade7cb70 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -546,6 +546,8 @@ static QemuThread *decompress_threads; static QemuMutex decomp_done_lock; static QemuCond decomp_done_cond; +static int ram_save_host_page_urgent(PageSearchStatus *pss); + static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block, ram_addr_t offset, uint8_t *source_buf); @@ -560,6 +562,16 @@ static void pss_init(PageSearchStatus *pss, RAMBlock *rb, ram_addr_t page) pss->complete_round = false; } +/* + * Check whether two PSSs are actively sending the same page. Return true + * if it is, false otherwise. + */ +static bool pss_overlap(PageSearchStatus *pss1, PageSearchStatus *pss2) +{ + return pss1->host_page_sending && pss2->host_page_sending && + (pss1->host_page_start == pss2->host_page_start); +} + static void *do_data_compress(void *opaque) { CompressParam *param = opaque; @@ -2260,6 +2272,57 @@ int ram_save_queue_pages(const char *rbname, ram_addr_t start, ram_addr_t len) return -1; } + /* + * When with postcopy preempt, we send back the page directly in the + * rp-return thread. + */ + if (postcopy_preempt_active()) { + ram_addr_t page_start = start >> TARGET_PAGE_BITS; + size_t page_size = qemu_ram_pagesize(ramblock); + PageSearchStatus *pss = &ram_state->pss[RAM_CHANNEL_POSTCOPY]; + int ret = 0; + + qemu_mutex_lock(&rs->bitmap_mutex); + + pss_init(pss, ramblock, page_start); + /* + * Always use the preempt channel, and make sure it's there. It's + * safe to access without lock, because when rp-thread is running + * we should be the only one who operates on the qemufile + */ + pss->pss_channel = migrate_get_current()->postcopy_qemufile_src; + pss->postcopy_requested = true; + assert(pss->pss_channel); + + /* + * It must be either one or multiple of host page size. Just + * assert; if something wrong we're mostly split brain anyway. + */ + assert(len % page_size == 0); + while (len) { + if (ram_save_host_page_urgent(pss)) { + error_report("%s: ram_save_host_page_urgent() failed: " + "ramblock=%s, start_addr=0x"RAM_ADDR_FMT, + __func__, ramblock->idstr, start); + ret = -1; + break; + } + /* + * NOTE: after ram_save_host_page_urgent() succeeded, pss->page + * will automatically be moved and point to the next host page + * we're going to send, so no need to update here. + * + * Normally QEMU never sends >1 host page in requests, so + * logically we don't even need that as the loop should only + * run once, but just to be consistent. + */ + len -= page_size; + }; + qemu_mutex_unlock(&rs->bitmap_mutex); + + return ret; + } + struct RAMSrcPageRequest *new_entry = g_new0(struct RAMSrcPageRequest, 1); new_entry->rb = ramblock; @@ -2537,6 +2600,55 @@ static void pss_host_page_finish(PageSearchStatus *pss) pss->host_page_start = pss->host_page_end = 0; } +/* + * Send an urgent host page specified by `pss'. Need to be called with + * bitmap_mutex held. + * + * Returns 0 if save host page succeeded, false otherwise. + */ +static int ram_save_host_page_urgent(PageSearchStatus *pss) +{ + bool page_dirty, sent = false; + RAMState *rs = ram_state; + int ret = 0; + + trace_postcopy_preempt_send_host_page(pss->block->idstr, pss->page); + pss_host_page_prepare(pss); + + /* + * If precopy is sending the same page, let it be done in precopy, or + * we could send the same page in two channels and none of them will + * receive the whole page. + */ + if (pss_overlap(pss, &ram_state->pss[RAM_CHANNEL_PRECOPY])) { + trace_postcopy_preempt_hit(pss->block->idstr, + pss->page << TARGET_PAGE_BITS); + return 0; + } + + do { + page_dirty = migration_bitmap_clear_dirty(rs, pss->block, pss->page); + + if (page_dirty) { + /* Be strict to return code; it must be 1, or what else? */ + if (ram_save_target_page(rs, pss) != 1) { + error_report_once("%s: ram_save_target_page failed", __func__); + ret = -1; + goto out; + } + sent = true; + } + pss_find_next_dirty(pss); + } while (pss_within_range(pss)); +out: + pss_host_page_finish(pss); + /* For urgent requests, flush immediately if sent */ + if (sent) { + qemu_fflush(pss->pss_channel); + } + return ret; +} + /** * ram_save_host_page: save a whole host page * -- 2.38.1