From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50482) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ctUsS-000362-DC for qemu-devel@nongnu.org; Thu, 30 Mar 2017 03:52:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ctUsR-0000Ze-Er for qemu-devel@nongnu.org; Thu, 30 Mar 2017 03:52:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52188) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ctUsR-0000XS-6E for qemu-devel@nongnu.org; Thu, 30 Mar 2017 03:52:15 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 215C2F622F for ; Thu, 30 Mar 2017 07:52:14 +0000 (UTC) Date: Thu, 30 Mar 2017 15:52:06 +0800 From: Peter Xu Message-ID: <20170330075206.GA21915@pxdev.xzpeter.org> References: <20170323204544.12015-1-quintela@redhat.com> <20170323204544.12015-38-quintela@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170323204544.12015-38-quintela@redhat.com> Subject: Re: [Qemu-devel] [PATCH 37/51] ram: Move compression_switch to RAMState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: qemu-devel@nongnu.org, dgilbert@redhat.com On Thu, Mar 23, 2017 at 09:45:30PM +0100, Juan Quintela wrote: > Rename it to preffer_xbzrle that is a more descriptive name. s/preffer/prefer/? > > Signed-off-by: Juan Quintela > --- > migration/ram.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index 6a39704..591cf89 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -217,6 +217,9 @@ struct RAMState { > uint64_t dirty_pages_rate; > /* Count of requests incoming from destination */ > uint64_t postcopy_requests; > + /* Should we move to xbzrle after the 1st round > + of compression */ > + bool preffer_xbzrle; > /* protects modification of the bitmap */ > QemuMutex bitmap_mutex; > /* Ram Bitmap protected by RCU */ > @@ -335,7 +338,6 @@ static QemuCond comp_done_cond; > /* The empty QEMUFileOps will be used by file in CompressParam */ > static const QEMUFileOps empty_ops = { }; > > -static bool compression_switch; > static DecompressParam *decomp_param; > static QemuThread *decompress_threads; > static QemuMutex decomp_done_lock; > @@ -419,7 +421,6 @@ void migrate_compress_threads_create(void) > if (!migrate_use_compression()) { > return; > } > - compression_switch = true; > thread_count = migrate_compress_threads(); > compress_threads = g_new0(QemuThread, thread_count); > comp_param = g_new0(CompressParam, thread_count); > @@ -1091,7 +1092,7 @@ static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss, > * point. In theory, xbzrle can do better than compression. > */ > flush_compressed_data(rs); > - compression_switch = false; > + rs->preffer_xbzrle = true; > } > } > /* Didn't find anything this time, but try again on the new block */ > @@ -1323,7 +1324,7 @@ static int ram_save_target_page(RAMState *rs, MigrationState *ms, > /* Check the pages is dirty and if it is send it */ > if (migration_bitmap_clear_dirty(rs, dirty_ram_abs)) { > unsigned long *unsentmap; > - if (compression_switch && migrate_use_compression()) { > + if (!rs->preffer_xbzrle && migrate_use_compression()) { IIUC this prefer_xbzrle can be dynamically calculated by existing states: static inline bool ram_compression_active(RAMState *rs) { /* * If xbzrle is on, stop using the data compression after first * round of migration even if compression is enabled. In theory, * xbzrle can do better than compression. */ return migrate_use_compression() && \ (rs->ram_bulk_stage || !migrate_use_xbzrle()); } Then this line can be written as: if (ram_compression_active(rs)) { And if so, we can get rid of prefer_xbzrle, right? Having prefer_xbzrle should be slightly faster though, since it'll at least cache the above calculation. Thanks, > res = ram_save_compressed_page(rs, ms, pss, last_stage); > } else { > res = ram_save_page(rs, ms, pss, last_stage); > -- > 2.9.3 > > -- peterx