On 04/18/2012 08:12 PM, Anthony Liguori wrote: > Hi, > > Just to avoid any 1.1 migration "surprises", I view this series as 1.2 > material. I'm reluctant to make any protocol changes this late in the > release process (assuming this series got all the necessary review/ack in the > next 1.5 weeks). > > If anyone has a strong feeling differently, now's the time to speak up (as > opposed to during the -rc phase). Hi Anthony,
I was indeed aiming this series for 1.2. Cheers, Orit > > Regards, > > Anthony Liguori > > > On 04/11/2012 01:49 PM, Orit Wasserman wrote: >> Changes from v8: >> Implement more effiecent cache_resize method >> fix set_cachesize command comments >> >> Changes from v7: >> Copy current page before encoding it, this will prevents page content >> change during the encoding. >> Allow changing the cache size during an active migration. >> Fix comments by Avi. >> >> Changes from v6: >> 1) add assert checks to ULEB encoding/decoding >> 2) no need to send last zero run >> >> Changes from v5: >> 1) Add migration capabilities >> 2) Use ULEB to encode run length >> 3) Do not send unmodified (dirty) page >> 3) Fix other patch comments >> >> Using GCache or GHashTable requires allocating new buffer on every content >> change, >> so I decided to keep the simple cache implementation. >> >> Changes from v4: >> 1) Rebase >> 2) divide patch into 9 patches >> 3) move memory allocation into cache_insert >> >> Future work : >> Use SSE for encoding. >> Page ranking acording to their dirty rate and automatic >> activation/deactivation of the feature - will be sent in a separate patch >> series. >> >> By using XBZRLE (Xor Based Zero Run Length Encoding) we can reduce VM >> downtime >> and total live-migration time of VMs running memory write intensive workloads >> typical of large enterprise applications such as SAP ERP Systems, and >> generally >> speaking for any application with a sparse memory update pattern. >> >> The compression format uses the fact that we will have many zero (zero >> represents >> an unchanged value). >> We repesent the page data delta by zero and non zero runs. >> We represent a zero run with it's length (in bytes). >> We represent a non zero run with it's length (in bytes) and the data. >> The run length is encoded using ULEB128 (http://en.wikipedia.org/wiki/LEB128) >> >> page = zrun nzrun >> | zrun nzrun page >> >> zrun = length >> >> nzrun = length byte... >> >> length = uleb128 encoded integer >> >> On the sender side XBZRLE is used as a compact delta encoding of page >> updates, >> retrieving the old page content from an LRU cache (default size of 512 MB). >> The >> receiving side uses the existing page content and XBZRLE to decode the new >> page >> content. >> >> This is a more compact way to store the delta than the previous version. >> >> This work was originally based on research results published VEE 2011: >> Evaluation of >> Delta Compression Techniques for Efficient Live Migration of Large Virtual >> Machines by Benoit, Svard, Tordsson and Elmroth. Additionally the delta >> encoder >> XBRLE was improved further using XBZRLE instead. >> >> XBZRLE has a sustained bandwidth of 2-2.5 GB/s for typical workloads making >> it >> ideal for in-line, real-time encoding such as is needed for live-migration. >> >> A typical usage scenario: >> {qemu} migrate_set_cachesize 256m >> {qemu} migrate -d -x tcp:destination.host:4444 >> {qemu} info migrate >> ... >> transferred ram-duplicate: A kbytes >> transferred ram-normal: B kbytes >> transferred ram-xbrle: C kbytes >> overflow ram-xbrle: D pages >> cache-miss ram-xbrle: E pages >> >> Testing: live migration with XBZRLE completed in 110 seconds, without live >> migration was not able to complete. >> >> A simple synthetic memory r/w load generator: >> .. include<stdlib.h> >> .. include<stdio.h> >> .. int main() >> .. { >> .. char *buf = (char *) calloc(4096, 4096); >> .. while (1) { >> .. int i; >> .. for (i = 0; i< 4096 * 4; i++) { >> .. buf[i * 4096 / 4]++; >> .. } >> .. printf("."); >> .. } >> .. } >> >> Signed-off-by: Benoit Hudzia<benoit.hud...@sap.com> >> Signed-off-by: Petter Svard<pett...@cs.umu.se> >> Signed-off-by: Aidan Shribman<aidan.shrib...@sap.com> >> >> Orit Wasserman (10): >> Add cache handling functions >> Add uleb encoding/decoding functions >> Add save_block_hdr function >> Add host_from_stream_offset_versioned function >> Add MigrationParams structure >> Add XBZRLE to ram_save_block and ram_save_live >> Add XBZRLE option to migrate command >> Add migration capabilites >> Add set_cachesize command >> Add XBZRLE statistics >> >> arch_init.c | 521 >> ++++++++++++++++++++++++++++++++++++++++++++++++++--- >> block-migration.c | 8 +- >> hmp-commands.hx | 35 +++- >> hmp.c | 48 +++++- >> hmp.h | 2 + >> migration.c | 92 +++++++++- >> migration.h | 32 +++- >> monitor.c | 7 + >> qapi-schema.json | 64 +++++++- >> qemu-common.h | 1 + >> qmp-commands.hx | 78 ++++++++- >> savevm.c | 133 +++++++++++++- >> sysemu.h | 3 +- >> vmstate.h | 2 +- >> 14 files changed, 969 insertions(+), 57 deletions(-) >> > >
