61 lines
2.6 KiB
Diff
61 lines
2.6 KiB
Diff
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From 40d962d80b6f2e9d04428c5d1944834de1208fac Mon Sep 17 00:00:00 2001
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From: Harald Sitter <sitter@kde.org>
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Date: Wed, 12 Sep 2018 16:58:04 +0200
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Subject: [PATCH] [sftp] bump pending request count from 1 to 128
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Summary:
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with the previous value we basically did sync reading which means that
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network and cyrptographic overhead head a huge impact on throughput.
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meanwhile the perfect way to use asyncness is to schedule a whole bunch of
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requests before starting to read.
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previously this was documented as auto-adjusting, which it never was,
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there's also little to be gained from adjusting this value on the fly.
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more requests in most scenarios will simply mean a larger RAM footprint as
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more data potentially sits in libssh waiting to be read. with 128 requests
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that'd be ~8mb (assuming the file transferred is that large)
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this improves read performance with libssh 0.8 by up to 20 times for large
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files. read performance with libssh 0.6 is 2 to 3 times better.
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the faster the connection the higher the gain of course.
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128 gives somewhat competitive performance results compared to openssh's
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ssh implementations while not having too large a footprint.
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in raw numbers: a local link read was averaging around 10mb/s on both
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libssh versions. with 128 requests this goes up to 200. competitive is
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between 200 and 300 it seems (obviously all specific to my system)
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CHANGELOG: sftp file reading is now up to 20 times faster
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Reviewers: broulik
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Reviewed By: broulik
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Differential Revision: https://phabricator.kde.org/D15452
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---
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sftp/kio_sftp.h | 7 ++++---
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1 file changed, 4 insertions(+), 3 deletions(-)
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diff --git a/sftp/kio_sftp.h b/sftp/kio_sftp.h
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index cc6b9e09..e5639970 100644
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--- a/sftp/kio_sftp.h
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+++ b/sftp/kio_sftp.h
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@@ -141,10 +141,11 @@ private: // Private variables
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* @param file the sftp_file object which should be transferred.
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* @param sb the attributes of that sftp_file object.
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* @param maxPendingRequests the maximum number of parallel requests to start with.
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- * The number will be adjusted automatically depending
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- * on the connection speed.
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+ * The more are pending the higher the potential memory
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+ * foot print, however if the connection allows it
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+ * we'll get better throughput.
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*/
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- GetRequest(sftp_file file, sftp_attributes sb, ushort maxPendingRequests = 1);
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+ GetRequest(sftp_file file, sftp_attributes sb, ushort maxPendingRequests = 128);
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/**
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* Removes all pending requests and closes the SFTP channel and attributes
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* in order to avoid memory leaks.
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--
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2.18.0
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