nbdkit 1.22 provides API_VERSION 2 and parallel threading model for the python plugin. This version is available in RHEL AV 8.3.0. Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; --- v2v/output_rhv_upload.ml | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/v2v/output_rhv_upload.ml b/v2v/output_rhv_upload.ml index b5cc95b9..40768519 100644 --- a/v2v/output_rhv_upload.ml +++ b/v2v/output_rhv_upload.ml @@ -84,11 +84,11 @@ let parse_output_options options = { rhv_cafile; rhv_cluster; rhv_direct; rhv_verifypeer; rhv_disk_uuids } -(* In theory even very old versions of nbdkit might work, but as - * with [Nbdkit_sources] check for at least 1.12. +(* We need nbdkit >= 1.22 for API_VERSION 2 and parallel threading model + * in the python plugin. *) -let nbdkit_min_version = (1, 12, 0) -let nbdkit_min_version_string = "1.12.0" +let nbdkit_min_version = (1, 22, 0) +let nbdkit_min_version_string = "1.22.0" let nbdkit_python_plugin = Config.nbdkit_python_plugin let pidfile_timeout = 30 -- 2.26.2

imageio does not have a FUA flag, but we can emulate it using the flush feature. With flush=y, write or zero will issue a NBD_CMD_FLUSH at the end, so the call returns only after the data is flushed to storage. The plugin reports now that it supports FUA (based on can_flush), and when FUA flag is set, it emulates fua by setting flush query (PUT) or flag (PATCH). For example, this nbd command: NBD_CMD_WRITE flags=NBD_CMD_FUA_FLAG Is translated to this http request: PUT /path?flush=y On imageio server, this translates back to: NBD_CMD_WRITE flags=0 NBD_CMD_FLUSH Imageio server uses preallocated buffer per connection. If the write request is bigger than the buffer, it sends multiple write commands. The request returns only when the flush is completed. Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; --- v2v/rhv-upload-plugin.py | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/v2v/rhv-upload-plugin.py b/v2v/rhv-upload-plugin.py index 0f8101dd..1c6f0603 100644 --- a/v2v/rhv-upload-plugin.py +++ b/v2v/rhv-upload-plugin.py @@ -161,6 +161,12 @@ def can_flush(h): return h['can_flush'] +@failing +def can_fua(h): + # imageio flush feature is is compatible with NBD_CMD_FLAG_FUA. + return h['can_flush'] + + @failing def get_size(h): return params['disk_size'] @@ -231,7 +237,9 @@ def pwrite(h, buf, offset, flags): count = len(buf) - http.putrequest("PUT", h['path'] + "?flush=n") + flush = "y" if (h['can_flush'] and (flags & nbdkit.FLAG_FUA)) else "n" + + http.putrequest("PUT", h['path'] + "?flush=" + flush) # The oVirt server only uses the first part of the range, and the # content-length. http.putheader("Content-Range", "bytes %d-%d/*" % (offset, offset + count - 1)) @@ -260,14 +268,16 @@ def zero(h, count, offset, flags): # so nbdkit could call this even if the server doesn't support # zeroing. If this is the case we must emulate. if not h['can_zero']: - emulate_zero(h, count, offset) + emulate_zero(h, count, offset, flags) return + flush = bool(h['can_flush'] and (flags & nbdkit.FLAG_FUA)) + # Construct the JSON request for zeroing. buf = json.dumps({'op': "zero", 'offset': offset, 'size': count, - 'flush': False}).encode() + 'flush': flush}).encode() headers = {"Content-Type": "application/json", "Content-Length": str(len(buf))} @@ -283,10 +293,12 @@ def zero(h, count, offset, flags): r.read() -def emulate_zero(h, count, offset): +def emulate_zero(h, count, offset, flags): http = h['http'] - http.putrequest("PUT", h['path']) + flush = "y" if (h['can_flush'] and (flags & nbdkit.FLAG_FUA)) else "n" + + http.putrequest("PUT", h['path'] + "?flush=" + flush) http.putheader("Content-Range", "bytes %d-%d/*" % (offset, offset + count - 1)) http.putheader("Content-Length", str(count)) -- 2.26.2

Use multiple connections to imageio server to speed up the transfer. Connections are managed via a thread safe queue. Threads remove a connection from the queue for every request, and put it back when at the end of the request. Only one thread can access the connection at the same time. Threads are accessing existing values in the handle dict, like h["path"]. They may also modify h["failed"] on errors. These operations are thread safe and do not require additional locking. Sending flush request is more tricky; imageio server does not guarantee consistency for multiple for connections, so we need to send flush command for every connection. Since flush may be called when there are in-flight requests, we wait until all in-flight request are done before sending a flush. While flushing, the connection pool is empty so new requests will block on the queue until the flush is completed. Closing is done in a similar way, waiting until all in-flight requests are done and closing all connections. Testing shows that we requests are spread over 4 connections, but performance is worse. Connection time increased from 5.36 seconds to 7.08 seconds (32% slower). [connection 1 ops, 7.053520 s] [dispatch 548 ops, 1.188910 s] [write 469 ops, 1.014646 s, 332.75 MiB, 327.95 MiB/s] [zero 77 ops, 0.058495 s, 1.13 GiB, 19.29 GiB/s] [flush 2 ops, 0.000291 s] [connection 1 ops, 7.085039 s] [dispatch 548 ops, 1.097437 s] [write 478 ops, 0.924214 s, 323.25 MiB, 349.76 MiB/s] [zero 68 ops, 0.052265 s, 1.22 GiB, 23.43 GiB/s] [flush 2 ops, 0.000258 s] [connection 1 ops, 7.037253 s] [dispatch 547 ops, 1.111386 s] [write 477 ops, 0.959592 s, 343.25 MiB, 357.70 MiB/s] [zero 68 ops, 0.047005 s, 1.20 GiB, 25.44 GiB/s] [flush 2 ops, 0.000266 s] [connection 1 ops, 7.045538 s] [dispatch 548 ops, 1.191029 s] [write 482 ops, 1.041125 s, 347.12 MiB, 333.41 MiB/s] [zero 64 ops, 0.045171 s, 1.14 GiB, 25.16 GiB/s] [flush 2 ops, 0.000210 s] Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; --- v2v/rhv-upload-plugin.py | 298 +++++++++++++++++++++++++-------------- 1 file changed, 192 insertions(+), 106 deletions(-) diff --git a/v2v/rhv-upload-plugin.py b/v2v/rhv-upload-plugin.py index 20477c91..2b0178a9 100644 --- a/v2v/rhv-upload-plugin.py +++ b/v2v/rhv-upload-plugin.py @@ -21,20 +21,28 @@ import functools import inspect import json import logging +import queue import socket import ssl import sys import time +from contextlib import contextmanager from http.client import HTTPSConnection, HTTPConnection from urllib.parse import urlparse +import nbdkit + import ovirtsdk4 as sdk import ovirtsdk4.types as types # Using version 2 supporting the buffer protocol for better performance. API_VERSION = 2 +# Maximum number of connection to imageio server. Based on testing with imageio +# client, this give best performance. +MAX_CONNECTIONS = 4 + # Timeout to wait for oVirt disks to change status, or the transfer # object to finish initializing [seconds]. timeout = 5 * 60 @@ -61,6 +69,14 @@ def config_complete(): raise RuntimeError("missing configuration parameters") +def thread_model(): + """ + Using parallel model to speed up transfer with multiple connections to + imageio server. + """ + return nbdkit.THREAD_MODEL_PARALLEL + + def debug(s): if params['verbose']: print(s, file=sys.stderr) @@ -129,7 +145,7 @@ def open(readonly): # See https://bugzilla.redhat.com/1916176. http.close() - http = optimize_http(http, host, options) + pool = create_http_pool(destination_url, host, options) except: cancel_transfer(connection, transfer) raise @@ -147,7 +163,8 @@ def open(readonly): 'disk_id': disk.id, 'transfer': transfer, 'failed': False, - 'http': http, + 'pool': pool, + 'connections': pool.qsize(), 'path': destination_url.path, } @@ -202,69 +219,67 @@ def request_failed(r, msg): @failing def pread(h, buf, offset, flags): count = len(buf) - http = h['http'] - headers = {"Range": "bytes=%d-%d" % (offset, offset + count - 1)} - http.request("GET", h['path'], headers=headers) - r = http.getresponse() - # 206 = HTTP Partial Content. - if r.status != 206: - request_failed(r, - "could not read sector offset %d size %d" % - (offset, count)) - - content_length = int(r.getheader("content-length")) - if content_length != count: - # Should never happen. - request_failed(r, - "unexpected Content-Length offset %d size %d got %d" % - (offset, count, content_length)) - - with memoryview(buf) as view: - got = 0 - while got < count: - n = r.readinto(view[got:]) - if n == 0: - request_failed(r, - "short read offset %d size %d got %d" % - (offset, count, got)) - got += n + with http_context(h) as http: + http.request("GET", h['path'], headers=headers) + + r = http.getresponse() + # 206 = HTTP Partial Content. + if r.status != 206: + request_failed(r, + "could not read sector offset %d size %d" % + (offset, count)) + + content_length = int(r.getheader("content-length")) + if content_length != count: + # Should never happen. + request_failed(r, + "unexpected Content-Length offset %d size %d got %d" % + (offset, count, content_length)) + + with memoryview(buf) as view: + got = 0 + while got < count: + n = r.readinto(view[got:]) + if n == 0: + request_failed(r, + "short read offset %d size %d got %d" % + (offset, count, got)) + got += n @failing def pwrite(h, buf, offset, flags): - http = h['http'] - count = len(buf) flush = "y" if (h['can_flush'] and (flags & nbdkit.FLAG_FUA)) else "n" - http.putrequest("PUT", h['path'] + "?flush=" + flush) - # The oVirt server only uses the first part of the range, and the - # content-length. - http.putheader("Content-Range", "bytes %d-%d/*" % (offset, offset + count - 1)) - http.putheader("Content-Length", str(count)) - http.endheaders() + with http_context(h) as http: + http.putrequest("PUT", h['path'] + "?flush=" + flush) + # The oVirt server only uses the first part of the range, and the + # content-length. + http.putheader("Content-Range", "bytes %d-%d/*" % + (offset, offset + count - 1)) + http.putheader("Content-Length", str(count)) + http.endheaders() - try: - http.send(buf) - except BrokenPipeError: - pass + try: + http.send(buf) + except BrokenPipeError: + pass - r = http.getresponse() - if r.status != 200: - request_failed(r, - "could not write sector offset %d size %d" % - (offset, count)) + r = http.getresponse() + if r.status != 200: + request_failed(r, + "could not write sector offset %d size %d" % + (offset, count)) - r.read() + r.read() @failing def zero(h, count, offset, flags): - http = h['http'] - # Unlike the trim and flush calls, there is no 'can_zero' method # so nbdkit could call this even if the server doesn't support # zeroing. If this is the case we must emulate. @@ -283,67 +298,68 @@ def zero(h, count, offset, flags): headers = {"Content-Type": "application/json", "Content-Length": str(len(buf))} - http.request("PATCH", h['path'], body=buf, headers=headers) + with http_context(h) as http: + http.request("PATCH", h['path'], body=buf, headers=headers) - r = http.getresponse() - if r.status != 200: - request_failed(r, - "could not zero sector offset %d size %d" % - (offset, count)) + r = http.getresponse() + if r.status != 200: + request_failed(r, + "could not zero sector offset %d size %d" % + (offset, count)) - r.read() + r.read() def emulate_zero(h, count, offset, flags): - http = h['http'] - flush = "y" if (h['can_flush'] and (flags & nbdkit.FLAG_FUA)) else "n" - http.putrequest("PUT", h['path'] + "?flush=" + flush) - http.putheader("Content-Range", - "bytes %d-%d/*" % (offset, offset + count - 1)) - http.putheader("Content-Length", str(count)) - http.endheaders() + with http_context(h) as http: + http.putrequest("PUT", h['path'] + "?flush=" + flush) + http.putheader("Content-Range", + "bytes %d-%d/*" % (offset, offset + count - 1)) + http.putheader("Content-Length", str(count)) + http.endheaders() - try: - buf = bytearray(128 * 1024) - while count > len(buf): - http.send(buf) - count -= len(buf) - http.send(memoryview(buf)[:count]) - except BrokenPipeError: - pass + try: + buf = bytearray(128 * 1024) + while count > len(buf): + http.send(buf) + count -= len(buf) + http.send(memoryview(buf)[:count]) + except BrokenPipeError: + pass - r = http.getresponse() - if r.status != 200: - request_failed(r, - "could not write zeroes offset %d size %d" % - (offset, count)) + r = http.getresponse() + if r.status != 200: + request_failed(r, + "could not write zeroes offset %d size %d" % + (offset, count)) - r.read() + r.read() @failing def flush(h, flags): - http = h['http'] - # Construct the JSON request for flushing. buf = json.dumps({'op': "flush"}).encode() headers = {"Content-Type": "application/json", "Content-Length": str(len(buf))} - http.request("PATCH", h['path'], body=buf, headers=headers) + # Wait until all inflight requests are completed, and send a flush request + # for all imageio connections. - r = http.getresponse() - if r.status != 200: - request_failed(r, "could not flush") + for http in iter_http_pool(h): + http.request("PATCH", h['path'], body=buf, headers=headers) - r.read() + r = http.getresponse() + if r.status != 200: + request_failed(r, "could not flush") + + r.read() def close(h): - http = h['http'] connection = h['connection'] transfer = h['transfer'] disk_id = h['disk_id'] @@ -354,7 +370,7 @@ def close(h): # plugin exits. sys.stderr.flush() - http.close() + close_http_pool(h) # If the connection failed earlier ensure we cancel the transfer. Canceling # the transfer will delete the disk. @@ -659,6 +675,84 @@ def transfer_supports_format(): return "format" in sig.parameters +# Connection pool managment + + +def create_http_pool(url, host, options): + pool = queue.Queue() + + count = min(options["max_readers"], + options["max_writers"], + MAX_CONNECTIONS) + + debug("creating http pool connections=%d" % count) + + unix_socket = options["unix_socket"] if host is not None else None + + for i in range(count): + http = create_http(url, unix_socket=unix_socket) + pool.put(http) + + return pool + + +@contextmanager +def http_context(h): + """ + Context manager yielding an imageio http connection from the pool. Blocks + until a connection is available. + """ + pool = h["pool"] + http = pool.get() + try: + yield http + finally: + pool.put(http) + + +def iter_http_pool(h): + """ + Wait until all inflight requests are done, and iterate on imageio + connections. + + The pool is empty during iteration. New requests issued during iteration + will block until iteration is done. + """ + pool = h["pool"] + locked = [] + + # Lock the pool by taking the connection out. + while len(locked) < h["connections"]: + locked.append(pool.get()) + + try: + for http in locked: + yield http + finally: + # Unlock the pool by puting the connection back. + for http in locked: + pool.put(http) + + +def close_http_pool(h): + """ + Wait until all inflight requests are done, close all connections and remove + them from the pool. + + No request can be served by the pool after this call. + """ + debug("closing http pool") + + pool = h["pool"] + locked = [] + + while len(locked) < h["connections"]: + locked.append(pool.get()) + + for http in locked: + http.close() + + # oVirt imageio operations @@ -677,12 +771,20 @@ def parse_transfer_url(transfer): return urlparse(transfer.proxy_url) -def create_http(url): +def create_http(url, unix_socket=None): """ Create http connection for transfer url. Returns HTTPConnection. """ + if unix_socket: + debug("creating unix http connection socket=%r" % unix_socket) + try: + return UnixHTTPConnection(unix_socket) + except Exception as e: + # Very unlikely, but we can recover by using https. + debug("cannot create unix socket connection: %s" % e) + if url.scheme == "https": context = \ ssl.create_default_context(purpose=ssl.Purpose.SERVER_AUTH, @@ -691,8 +793,12 @@ def create_http(url): context.check_hostname = False context.verify_mode = ssl.CERT_NONE + debug("creating https connection host=%s port=%s" % + (url.hostname, url.port)) return HTTPSConnection(url.hostname, url.port, context=context) elif url.scheme == "http": + debug("creating http connection host=%s port=%s" % + (url.hostname, url.port)) return HTTPConnection(url.hostname, url.port) else: raise RuntimeError("unknown URL scheme (%s)" % url.scheme) @@ -730,23 +836,3 @@ def get_options(http, url): else: raise RuntimeError("could not use OPTIONS request: %d: %s" % (r.status, r.reason)) - - -def optimize_http(http, host, options): - """ - Return an optimized http connection using unix socket if we are connected - to imageio server on the local host and it features a unix socket. - """ - unix_socket = options['unix_socket'] - - if host is not None and unix_socket is not None: - try: - http = UnixHTTPConnection(unix_socket) - except Exception as e: - # Very unlikely failure, but we can recover by using the https - # connection. - debug("cannot create unix socket connection, using https: %s" % e) - else: - debug("optimizing connection using unix socket %r" % unix_socket) - - return http -- 2.26.2

qemu-img is using 8 parallel coroutines by default. I tested up to 16 parallel coroutines and it seems that 8 gives good results. nbdkit uses 16 threads by default. Testing nbdkit with qemu-img show that 8 threads give good results. Make nbdkit thread count configurable, and configure it to 8 threads in the rhv upload output. Testing rhv-upload-plugin show small improvement (~6%) in total connection time. Compared with last version using single connection, we are now 50% faster. Results are not stable, we need to test this with bigger images and real environment. [connection 1 ops, 3.561693 s] [dispatch 550 ops, 2.808350 s] [write 470 ops, 2.482875 s, 316.06 MiB, 127.30 MiB/s] [zero 78 ops, 0.178174 s, 1.26 GiB, 7.05 GiB/s] [flush 2 ops, 0.000211 s] [connection 1 ops, 3.561724 s] [dispatch 543 ops, 2.836738 s] [write 472 ops, 2.503561 s, 341.62 MiB, 136.46 MiB/s] [zero 69 ops, 0.162465 s, 1.12 GiB, 6.89 GiB/s] [flush 2 ops, 0.000181 s] [connection 1 ops, 3.566931 s] [dispatch 536 ops, 2.807226 s] [write 462 ops, 2.508345 s, 326.12 MiB, 130.02 MiB/s] [zero 72 ops, 0.141442 s, 1.30 GiB, 9.20 GiB/s] [flush 2 ops, 0.000158 s] [connection 1 ops, 3.564396 s] [dispatch 563 ops, 2.853623 s] [write 503 ops, 2.592482 s, 361.44 MiB, 139.42 MiB/s] [zero 58 ops, 0.113708 s, 1.01 GiB, 8.88 GiB/s] [flush 2 ops, 0.000149 s] Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; --- v2v/nbdkit.ml | 4 ++++ v2v/nbdkit.mli | 1 + v2v/output_rhv_upload.ml | 3 +++ 3 files changed, 8 insertions(+) diff --git a/v2v/nbdkit.ml b/v2v/nbdkit.ml index 46b20c9d..c7a92bf0 100644 --- a/v2v/nbdkit.ml +++ b/v2v/nbdkit.ml @@ -72,6 +72,7 @@ type cmd = { exportname : string option; readonly : bool; selinux_label : string option; + threads : int; verbose : bool; } @@ -84,6 +85,7 @@ let new_cmd = { exportname = None; readonly = false; selinux_label = None; + threads = 16; verbose = false; } @@ -93,6 +95,7 @@ let add_debug_flag cmd name value = let set_exportname cmd v = { cmd with exportname = Some v } let set_readonly cmd v = { cmd with readonly = v } let set_selinux_label cmd v = { cmd with selinux_label = v } +let set_threads cmd v = { cmd with threads = v } let set_verbose cmd v = { cmd with verbose = v } let set_plugin cmd v = { cmd with plugin = Some v } let add_filter cmd v = { cmd with filters = v :: cmd.filters } @@ -136,6 +139,7 @@ let run_unix cmd = add_arg "--newstyle"; add_arg "--pidfile"; add_arg pidfile; add_arg "--unix"; add_arg sock; + add_arg "--threads"; add_arg (string_of_int cmd.threads); (* Reduce verbosity in nbdkit >= 1.17.4. *) let version = version (config ()) in diff --git a/v2v/nbdkit.mli b/v2v/nbdkit.mli index d927fe40..85eb75b6 100644 --- a/v2v/nbdkit.mli +++ b/v2v/nbdkit.mli @@ -56,6 +56,7 @@ val add_debug_flag : cmd -> string -> string -> cmd val set_exportname : cmd -> string -> cmd val set_readonly : cmd -> bool -> cmd val set_selinux_label : cmd -> string option -> cmd +val set_threads : cmd -> int -> cmd val set_verbose : cmd -> bool -> cmd (** Set various command line flags. *) diff --git a/v2v/output_rhv_upload.ml b/v2v/output_rhv_upload.ml index a9dfe39b..dbef7011 100644 --- a/v2v/output_rhv_upload.ml +++ b/v2v/output_rhv_upload.ml @@ -208,6 +208,9 @@ class output_rhv_upload output_alloc output_conn let nbdkit_cmd = Nbdkit.set_plugin nbdkit_cmd nbdkit_python_plugin in let nbdkit_cmd = Nbdkit.add_arg nbdkit_cmd "script" (Python_script.path plugin_script) in + (* Match number of parallel coroutines in qemu-img *) + let nbdkit_cmd = Nbdkit.set_threads nbdkit_cmd 8 in + let nbdkit_cmd = if have_selinux then (* Label the socket so qemu can open it. *) -- 2.26.2