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From 7e37aba0cce21ad9abdf742528e605fa1cbc2e5e Mon Sep 17 00:00:00 2001
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From: Nir Soffer <nirsof@gmail.com>
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Date: Fri, 15 Jun 2018 22:57:32 +0300
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Subject: [PATCH] RHEL 7: v2v: rhv-upload: Disable Nagle algorithm
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When sending a PUT request, the http header may be sent in the first
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packet when calling con.endheaders(). When we send the first chunk, the
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kernel may delay the send because the header packet was not acked yet.
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We have seen PUT requests delayed by 40 milliseconds on the server side
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during virt-v2v upload to ovirt. Here is example log from current RHEL
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virt-v2v version, uploading to RHV 4.2.3:
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2018-06-12 17:04:01,750 INFO (Thread-2) [images] Writing 52736 bytes
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at offset 0 flush False to /path/to/image for ticket
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374bec27-930d-4097-8e41-e4bc23324eb0
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2018-06-12 17:04:01,790 INFO (Thread-2) [directio] Operation stats:
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<Clock(total=0.04, read=0.04, write=0.00)>
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The server spent 40 milliseconds reading 52736 bytes form
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rhv_upload_plugin running on the same host.
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This issue was fixed in python 3.5 by using the TCP_NO_DELAY option
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after connecting[1]. I backported this change from python 3.5.
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I tested the same change using imageio example upload script. With this
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change and with optimized PATCH requests, upload time of 4G sparse image
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was reduced from 7 minutes to 1 minute.
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See this ovirt patch for more details:
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https://gerrit.ovirt.org/#/c/92276/
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This change is needed only for python 2.
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[1] https://bugs.python.org/issue23302
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---
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v2v/rhv-upload-plugin.py | 14 +++++++++++++-
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1 file changed, 13 insertions(+), 1 deletion(-)
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diff --git a/v2v/rhv-upload-plugin.py b/v2v/rhv-upload-plugin.py
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index 2e8486848..9e71021ea 100644
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--- a/v2v/rhv-upload-plugin.py
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+++ b/v2v/rhv-upload-plugin.py
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@@ -26,7 +26,7 @@ import sys
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import time
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import errno
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-from httplib import HTTPSConnection, HTTPConnection
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+from httplib import HTTPSConnection as _HTTPSConnection, HTTPConnection
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from urlparse import urlparse
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import ovirtsdk4 as sdk
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@@ -52,6 +52,18 @@ def byteify(input):
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return input
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params = None
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+class HTTPSConnection(_HTTPSConnection):
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+ def connect(self):
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+ """
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+ Using TCP_NO_DELAY avoids delays when sending small payload, such as
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+ ovirt PATCH requests.
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+
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+ This issue was fixed in python 3.5, see:
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+ https://bugs.python.org/issue23302
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+ """
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+ _HTTPSConnection.connect(self)
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+ self.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
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+
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def config(key, value):
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global params
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--
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2.21.0
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