From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54483) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eqyaz-0007W8-RA for qemu-devel@nongnu.org; Wed, 28 Feb 2018 05:04:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eqyav-0003Lz-Hh for qemu-devel@nongnu.org; Wed, 28 Feb 2018 05:04:21 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:56518 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eqyav-0003Li-B3 for qemu-devel@nongnu.org; Wed, 28 Feb 2018 05:04:17 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id AF6AD402290A for ; Wed, 28 Feb 2018 10:04:06 +0000 (UTC) Date: Wed, 28 Feb 2018 18:03:56 +0800 From: Peter Xu Message-ID: <20180228100356.GE27381@xz-mi> References: <20180216131625.9639-1-dgilbert@redhat.com> <20180216131625.9639-18-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180216131625.9639-18-dgilbert@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 17/29] vhost+postcopy: Send requests to source for shared pages List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" Cc: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, marcandre.lureau@redhat.com, imammedo@redhat.com, mst@redhat.com, quintela@redhat.com, aarcange@redhat.com On Fri, Feb 16, 2018 at 01:16:13PM +0000, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" > > Send requests back to the source for shared page requests. > > Signed-off-by: Dr. David Alan Gilbert > --- > migration/migration.h | 2 ++ > migration/postcopy-ram.c | 31 ++++++++++++++++++++++++++++--- > migration/postcopy-ram.h | 3 +++ > migration/trace-events | 2 ++ > 4 files changed, 35 insertions(+), 3 deletions(-) > > diff --git a/migration/migration.h b/migration/migration.h > index d158e62cf2..457bf37ec2 100644 > --- a/migration/migration.h > +++ b/migration/migration.h > @@ -46,6 +46,8 @@ struct MigrationIncomingState { > int userfault_quit_fd; > QEMUFile *to_src_file; > QemuMutex rp_mutex; /* We send replies from multiple threads */ > + /* RAMBlock of last request sent to source */ > + RAMBlock *last_rb; > void *postcopy_tmp_page; > void *postcopy_tmp_zero_page; > /* PostCopyFD's for external userfaultfds & handlers of shared memory */ > diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c > index d118b78bf5..277ff749a0 100644 > --- a/migration/postcopy-ram.c > +++ b/migration/postcopy-ram.c > @@ -534,6 +534,31 @@ static int ram_block_enable_notify(const char *block_name, void *host_addr, > return 0; > } > > +/* > + * Callback from shared fault handlers to ask for a page, > + * the page must be specified by a RAMBlock and an offset in that rb > + */ > +int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, > + uint64_t client_addr, uint64_t rb_offset) > +{ > + size_t pagesize = qemu_ram_pagesize(rb); > + uint64_t aligned_rbo = rb_offset & ~(pagesize - 1); > + MigrationIncomingState *mis = migration_incoming_get_current(); > + > + trace_postcopy_request_shared_page(pcfd->idstr, qemu_ram_get_idstr(rb), > + rb_offset); > + /* TODO: Check bitmap to see if we already have the page */ > + if (rb != mis->last_rb) { > + mis->last_rb = rb; > + migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb), > + aligned_rbo, pagesize); > + } else { > + /* Save some space */ > + migrate_send_rp_req_pages(mis, NULL, aligned_rbo, pagesize); > + } > + return 0; > +} > + So IIUC this can only be called within the page fault thread or there can be race. Is there a way to guarantee this? Or do we need a comment for that? > /* > * Handle faults detected by the USERFAULT markings > */ > @@ -544,9 +569,9 @@ static void *postcopy_ram_fault_thread(void *opaque) > int ret; > size_t index; > RAMBlock *rb = NULL; > - RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */ > > trace_postcopy_ram_fault_thread_entry(); > + mis->last_rb = NULL; /* last RAMBlock we sent part of */ > qemu_sem_post(&mis->fault_thread_sem); > > struct pollfd *pfd; > @@ -634,8 +659,8 @@ static void *postcopy_ram_fault_thread(void *opaque) > * Send the request to the source - we want to request one > * of our host page sizes (which is >= TPS) > */ > - if (rb != last_rb) { > - last_rb = rb; > + if (rb != mis->last_rb) { > + mis->last_rb = rb; > migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb), > rb_offset, qemu_ram_pagesize(rb)); > } else { > diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h > index dbc2ee1f2b..4c63f20df4 100644 > --- a/migration/postcopy-ram.h > +++ b/migration/postcopy-ram.h > @@ -162,5 +162,8 @@ struct PostCopyFD { > */ > void postcopy_register_shared_ufd(struct PostCopyFD *pcfd); > void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd); > +/* Callback from shared fault handlers to ask for a page */ > +int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, > + uint64_t client_addr, uint64_t offset); > > #endif > diff --git a/migration/trace-events b/migration/trace-events > index 1e617ad7a6..7c910b5479 100644 > --- a/migration/trace-events > +++ b/migration/trace-events > @@ -198,6 +198,8 @@ postcopy_ram_incoming_cleanup_closeuf(void) "" > postcopy_ram_incoming_cleanup_entry(void) "" > postcopy_ram_incoming_cleanup_exit(void) "" > postcopy_ram_incoming_cleanup_join(void) "" > +postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_offset) "for %s in %s offset 0x%"PRIx64 > + > save_xbzrle_page_skipping(void) "" > save_xbzrle_page_overflow(void) "" > ram_save_iterate_big_wait(uint64_t milliconds, int iterations) "big wait: %" PRIu64 " milliseconds, %d iterations" > -- > 2.14.3 > -- Peter Xu