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 B102FC0032E for ; Wed, 25 Oct 2023 14:04:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qveUQ-0007mg-7v; Wed, 25 Oct 2023 10:04:06 -0400 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 1qveUO-0007bb-As for qemu-devel@nongnu.org; Wed, 25 Oct 2023 10:04:04 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qveUL-0006Ll-5X for qemu-devel@nongnu.org; Wed, 25 Oct 2023 10:04:04 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id E560521BDA; Wed, 25 Oct 2023 14:03:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1698242639; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vSoAWgVIrsSqr2+T9mAqEYsU5ioQVDGRgysWtpYvtEU=; b=LoTLdsTD1keKuLAjRTXar+3PIu5Nghf58eOlagXUQPH9/xwkV4e7Zalexiijyy3/FoExs3 PSkJ/iiv1qX2z5bsE5hl45jGQ4uSl769e5xtTwQoJuoQ0FIVxXuXXkWdGOWV/RwYJZgoQ5 vHcjpjKPzJxBRcR6Ecrsx5h+eSwHgMY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1698242639; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vSoAWgVIrsSqr2+T9mAqEYsU5ioQVDGRgysWtpYvtEU=; b=1G+ioMyrb1go7nOpXfBSk11tefOf6pLN+dihE6IteMolA8Ge/2+U6mSaXElxEMgreyRHt3 L4JbRcfRfGzLWjDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 76FDD13524; Wed, 25 Oct 2023 14:03:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 0YC6EE8gOWUGEgAAMHmgww (envelope-from ); Wed, 25 Oct 2023 14:03:59 +0000 From: Fabiano Rosas To: =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, armbru@redhat.com, Juan Quintela , Peter Xu , Leonardo Bras , Claudio Fontana , Nikolay Borisov , Paolo Bonzini , David Hildenbrand , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v2 15/29] migration/ram: Add support for 'fixed-ram' outgoing migration In-Reply-To: References: <20231023203608.26370-1-farosas@suse.de> <20231023203608.26370-16-farosas@suse.de> Date: Wed, 25 Oct 2023 11:03:57 -0300 Message-ID: <87ttqeer3m.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [-7.10 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; BAYES_HAM(-3.00)[100.00%]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-3.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-1.00)[-1.000]; RCPT_COUNT_SEVEN(0.00)[11]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] Received-SPF: pass client-ip=195.135.220.28; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: 2.1.29 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 Daniel P. Berrang=C3=A9 writes: > On Mon, Oct 23, 2023 at 05:35:54PM -0300, Fabiano Rosas wrote: >> From: Nikolay Borisov >>=20 >> Implement the outgoing migration side for the 'fixed-ram' capability. >>=20 >> A bitmap is introduced to track which pages have been written in the >> migration file. Pages are written at a fixed location for every >> ramblock. Zero pages are ignored as they'd be zero in the destination >> migration as well. >>=20 >> The migration stream is altered to put the dirty pages for a ramblock >> after its header instead of having a sequential stream of pages that >> follow the ramblock headers. Since all pages have a fixed location, >> RAM_SAVE_FLAG_EOS is no longer generated on every migration iteration. >>=20 >> Without fixed-ram (current): >>=20 >> ramblock 1 header|ramblock 2 header|...|RAM_SAVE_FLAG_EOS|stream of >> pages (iter 1)|RAM_SAVE_FLAG_EOS|stream of pages (iter 2)|... > > Clearer to diagram this vertically I think > > --------------------- > | ramblock 1 header | > --------------------- > | ramblock 2 header | > --------------------- > | ... | > --------------------- > | ramblock n header | > --------------------- > | RAM_SAVE_FLAG_EOS | > --------------------- > | stream of pages | > | (iter 1) | > | ... | > --------------------- > | RAM_SAVE_FLAG_EOS | > --------------------- > | stream of pages | > | (iter 2) | > | ... | > --------------------- > | ... | > --------------------- >=20=20 > >>=20 >> With fixed-ram (new): >>=20 >> ramblock 1 header|ramblock 1 fixed-ram header|ramblock 1 pages (fixed >> offsets)|ramblock 2 header|ramblock 2 fixed-ram header|ramblock 2 >> pages (fixed offsets)|...|RAM_SAVE_FLAG_EOS > > If I'm reading the code correctly the new format has some padding > such that each "ramblock pages" region starts on a 1 MB boundary. > > eg so we get: > > -------------------------------- > | ramblock 1 header | > -------------------------------- > | ramblock 1 fixed-ram header | > -------------------------------- > | padding to next 1MB boundary | > | ... | > -------------------------------- > | ramblock 1 pages | > | ... | > -------------------------------- > | ramblock 2 header | > -------------------------------- > | ramblock 2 fixed-ram header | > -------------------------------- > | padding to next 1MB boundary | > | ... | > -------------------------------- > | ramblock 2 pages | > | ... | > -------------------------------- > | ... | > -------------------------------- > | RAM_SAVE_FLAG_EOS | > -------------------------------- > | ... | > ------------------------------- > >>=20 >> where: >> - ramblock header: the generic information for a ramblock, such as >> idstr, used_len, etc. >>=20 >> - ramblock fixed-ram header: the new information added by this >> feature: bitmap of pages written, bitmap size and offset of pages >> in the migration file. >>=20 >> Signed-off-by: Nikolay Borisov >> Signed-off-by: Fabiano Rosas >> --- >> include/exec/ramblock.h | 8 ++++ >> migration/options.c | 3 -- >> migration/ram.c | 98 ++++++++++++++++++++++++++++++++++++----- >> 3 files changed, 96 insertions(+), 13 deletions(-) >>=20 >> diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h >> index 69c6a53902..e0e3f16852 100644 >> --- a/include/exec/ramblock.h >> +++ b/include/exec/ramblock.h >> @@ -44,6 +44,14 @@ struct RAMBlock { >> size_t page_size; >> /* dirty bitmap used during migration */ >> unsigned long *bmap; >> + /* shadow dirty bitmap used when migrating to a file */ >> + unsigned long *shadow_bmap; >> + /* >> + * offset in the file pages belonging to this ramblock are saved, >> + * used only during migration to a file. >> + */ >> + off_t bitmap_offset; >> + uint64_t pages_offset; >> /* bitmap of already received pages in postcopy */ >> unsigned long *receivedmap; >>=20=20 >> diff --git a/migration/options.c b/migration/options.c >> index 2622d8c483..9f693d909f 100644 >> --- a/migration/options.c >> +++ b/migration/options.c >> @@ -271,12 +271,9 @@ bool migrate_events(void) >>=20=20 >> bool migrate_fixed_ram(void) >> { >> -/* >> MigrationState *s =3D migrate_get_current(); >>=20=20 >> return s->capabilities[MIGRATION_CAPABILITY_FIXED_RAM]; >> -*/ >> - return false; >> } >>=20=20 >> bool migrate_ignore_shared(void) >> diff --git a/migration/ram.c b/migration/ram.c >> index 92769902bb..152a03604f 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -1157,12 +1157,18 @@ static int save_zero_page(RAMState *rs, PageSear= chStatus *pss, >> return 0; >> } >>=20=20 >> + stat64_add(&mig_stats.zero_pages, 1); >> + >> + if (migrate_fixed_ram()) { >> + /* zero pages are not transferred with fixed-ram */ >> + clear_bit(offset >> TARGET_PAGE_BITS, pss->block->shadow_bmap); >> + return 1; >> + } >> + >> len +=3D save_page_header(pss, file, pss->block, offset | RAM_SAVE_= FLAG_ZERO); >> qemu_put_byte(file, 0); >> len +=3D 1; >> ram_release_page(pss->block->idstr, offset); >> - >> - stat64_add(&mig_stats.zero_pages, 1); >> ram_transferred_add(len); >>=20=20 >> /* >> @@ -1220,14 +1226,20 @@ static int save_normal_page(PageSearchStatus *ps= s, RAMBlock *block, >> { >> QEMUFile *file =3D pss->pss_channel; >>=20=20 >> - ram_transferred_add(save_page_header(pss, pss->pss_channel, block, >> - offset | RAM_SAVE_FLAG_PAGE)); >> - if (async) { >> - qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE, >> - migrate_release_ram() && >> - migration_in_postcopy()); >> + if (migrate_fixed_ram()) { >> + qemu_put_buffer_at(file, buf, TARGET_PAGE_SIZE, >> + block->pages_offset + offset); >> + set_bit(offset >> TARGET_PAGE_BITS, block->shadow_bmap); >> } else { >> - qemu_put_buffer(file, buf, TARGET_PAGE_SIZE); >> + ram_transferred_add(save_page_header(pss, pss->pss_channel, blo= ck, >> + offset | RAM_SAVE_FLAG_PAG= E)); >> + if (async) { >> + qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE, >> + migrate_release_ram() && >> + migration_in_postcopy()); >> + } else { >> + qemu_put_buffer(file, buf, TARGET_PAGE_SIZE); >> + } >> } >> ram_transferred_add(TARGET_PAGE_SIZE); >> stat64_add(&mig_stats.normal_pages, 1); >> @@ -2475,6 +2487,8 @@ static void ram_save_cleanup(void *opaque) >> block->clear_bmap =3D NULL; >> g_free(block->bmap); >> block->bmap =3D NULL; >> + g_free(block->shadow_bmap); >> + block->shadow_bmap =3D NULL; >> } >>=20=20 >> xbzrle_cleanup(); >> @@ -2842,6 +2856,7 @@ static void ram_list_init_bitmaps(void) >> */ >> block->bmap =3D bitmap_new(pages); >> bitmap_set(block->bmap, 0, pages); >> + block->shadow_bmap =3D bitmap_new(block->used_length >> TAR= GET_PAGE_BITS); >> block->clear_bmap_shift =3D shift; >> block->clear_bmap =3D bitmap_new(clear_bmap_size(pages, shi= ft)); >> } >> @@ -2979,6 +2994,44 @@ void qemu_guest_free_page_hint(void *addr, size_t= len) >> } >> } >>=20=20 >> +#define FIXED_RAM_HDR_VERSION 1 >> +struct FixedRamHeader { >> + uint32_t version; >> + uint64_t page_size; >> + uint64_t bitmap_offset; >> + uint64_t pages_offset; >> + /* end of v1 */ >> +} QEMU_PACKED; >> + >> +static void fixed_ram_insert_header(QEMUFile *file, RAMBlock *block) >> +{ >> + g_autofree struct FixedRamHeader *header; >> + size_t header_size, bitmap_size; >> + long num_pages; >> + >> + header =3D g_new0(struct FixedRamHeader, 1); >> + header_size =3D sizeof(struct FixedRamHeader); >> + >> + num_pages =3D block->used_length >> TARGET_PAGE_BITS; >> + bitmap_size =3D BITS_TO_LONGS(num_pages) * sizeof(unsigned long); >> + >> + /* >> + * Save the file offsets of where the bitmap and the pages should >> + * go as they are written at the end of migration and during the >> + * iterative phase, respectively. >> + */ >> + block->bitmap_offset =3D qemu_get_offset(file) + header_size; >> + block->pages_offset =3D ROUND_UP(block->bitmap_offset + >> + bitmap_size, 0x100000); > > The 0x100000 gives us our 1 MB alignment. > > This is quite an important thing, so can we put a nice clear > constant at the top of the file: > > /* Align fixed-ram pages data to the next 1 MB boundary */ > #define FIXED_RAM_PAGE_OFFSET_ALIGNMENT 0x100000 > >> @@ -3179,7 +3252,6 @@ out: >> qemu_put_be64(f, RAM_SAVE_FLAG_EOS); >> qemu_fflush(f); >> ram_transferred_add(8); >> - >> ret =3D qemu_file_get_error(f); >> } >> if (ret < 0) { > > Supurious whitspace change, possibly better in whatever patch > introduced it, or dropped ? > > > With regards, > Daniel I'll apply all the suggestions. Thanks!