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bh=fqIuVZSLTsHJ7zWi6B3v7Jb9InR1IFs/G1h6Do57lEU=; b=NQV0tSdcgUTpLBoja41fu9+il/E7JAoqtm14UCaNRfQuFGWlxoBDCKT5qJ7SH9sjR/Bxy4 mFnEClMsBAO7k6N6i+LN6LMD23V0zI/C19naKPoBIaDrXQx7opIGKO6KMBXdpiiyszuNgN rRVMXfOhExaZVTMowNhVdfoxEE5J9hc= X-MC-Unique: 1navZJ8CPoCd28yiKgubQQ-1 From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, alex.bennee@linaro.org, zhengchuan@huawei.com, stefanha@redhat.com, peterx@redhat.com Subject: [PULL 08/10] migration: Sync requested pages after postcopy recovery Date: Thu, 8 Oct 2020 20:10:44 +0100 Message-Id: <20201008191046.272549-9-dgilbert@redhat.com> In-Reply-To: <20201008191046.272549-1-dgilbert@redhat.com> References: <20201008191046.272549-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Peter Xu We synchronize the requested pages right after a postcopy recovery happens. This helps to synchronize the prioritized pages on source so that the fault= ed threads can be served faster. Reported-by: Xiaohui Li Signed-off-by: Peter Xu Message-Id: <20201002175336.30858-5-peterx@redhat.com> Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Dr. David Alan Gilbert --- migration/savevm.c | 57 ++++++++++++++++++++++++++++++++++++++++++ migration/trace-events | 1 + 2 files changed, 58 insertions(+) diff --git a/migration/savevm.c b/migration/savevm.c index d2e141f7b1..33acbba1a4 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -2011,6 +2011,49 @@ static int loadvm_postcopy_handle_run(MigrationIncom= ingState *mis) return LOADVM_QUIT; } =20 +/* We must be with page_request_mutex held */ +static gboolean postcopy_sync_page_req(gpointer key, gpointer value, + gpointer data) +{ + MigrationIncomingState *mis =3D data; + void *host_addr =3D (void *) key; + ram_addr_t rb_offset; + RAMBlock *rb; + int ret; + + rb =3D qemu_ram_block_from_host(host_addr, true, &rb_offset); + if (!rb) { + /* + * This should _never_ happen. However be nice for a migrating VM= to + * not crash/assert. Post an error (note: intended to not use *_o= nce + * because we do want to see all the illegal addresses; and this c= an + * never be triggered by the guest so we're safe) and move on next. + */ + error_report("%s: illegal host addr %p", __func__, host_addr); + /* Try the next entry */ + return FALSE; + } + + ret =3D migrate_send_rp_message_req_pages(mis, rb, rb_offset); + if (ret) { + /* Please refer to above comment. */ + error_report("%s: send rp message failed for addr %p", + __func__, host_addr); + return FALSE; + } + + trace_postcopy_page_req_sync(host_addr); + + return FALSE; +} + +static void migrate_send_rp_req_pages_pending(MigrationIncomingState *mis) +{ + WITH_QEMU_LOCK_GUARD(&mis->page_request_mutex) { + g_tree_foreach(mis->page_requested, postcopy_sync_page_req, mis); + } +} + static int loadvm_postcopy_handle_resume(MigrationIncomingState *mis) { if (mis->state !=3D MIGRATION_STATUS_POSTCOPY_RECOVER) { @@ -2033,6 +2076,20 @@ static int loadvm_postcopy_handle_resume(MigrationIn= comingState *mis) /* Tell source that "we are ready" */ migrate_send_rp_resume_ack(mis, MIGRATION_RESUME_ACK_VALUE); =20 + /* + * After a postcopy recovery, the source should have lost the postcopy + * queue, or potentially the requested pages could have been lost duri= ng + * the network down phase. Let's re-sync with the source VM by re-sen= ding + * all the pending pages that we eagerly need, so these threads won't = get + * blocked too long due to the recovery. + * + * Without this procedure, the faulted destination VM threads (waiting= for + * page requests right before the postcopy is interrupted) can keep ha= nging + * until the pages are sent by the source during the background copyin= g of + * pages, or another thread faulted on the same address accidentally. + */ + migrate_send_rp_req_pages_pending(mis); + return 0; } =20 diff --git a/migration/trace-events b/migration/trace-events index e4d5eb94ca..0fbfd2da60 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -49,6 +49,7 @@ vmstate_save(const char *idstr, const char *vmsd_name) "%= s, %s" vmstate_load(const char *idstr, const char *vmsd_name) "%s, %s" postcopy_pause_incoming(void) "" postcopy_pause_incoming_continued(void) "" +postcopy_page_req_sync(void *host_addr) "sync page req %p" =20 # vmstate.c vmstate_load_field_error(const char *field, int ret) "field \"%s\" load fa= iled, ret =3D %d" --=20 2.28.0