Subject: [ libssh2-Bugs-2819559 ] high cpu usage during SFTP copying (nonblock mode)

[ libssh2-Bugs-2819559 ] high cpu usage during SFTP copying (nonblock mode)

From: SourceForge.net <noreply_at_sourceforge.net>
Date: Fri, 10 Jul 2009 12:06:54 +0000

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Bugs item #2819559, was opened at 2009-07-10 16:06
Message generated for change (Tracker Item Submitted) made by mera-nn
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=703942&aid=2819559&group_id=125852

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Category: SFTP
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: mera (mera-nn)
Assigned to: Nobody/Anonymous (nobody)
Summary: high cpu usage during SFTP copying (nonblock mode)

Initial Comment:
Using test sftp copying binary , high cpu usage observed. Seems curl uses nonblock mode so sftp usage using curl library is high. Originally issue observed using curl library.

The logs below:

Using latest libssh2

[root_at_localhost simple]# pwd
/root/libssh2-1.1/example/simple

[root_at_localhost simple]#./sftp_write 192.168.35.75 user pass test.sftp /tmp/test.block
Fingerprint: 11 12 A1 54 1C 8D 65 40 DD 45 EC F9 12 25 A0 59
libssh2_sftp_init()!
libssh2_sftp_open()!
libssh2_sftp_open() is done, now send data!
all done

cpu usage is OK:
  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 2611 root 15 0 4808 1544 1264 S 11.7 0.1 0:01.48 lt-sftp_write

[root_at_localhost simple]# ./sftp_write_nonblock 192.168.35.75 user pass test.sftp /tmp/test.nonblock
Fingerprint: 11 12 A1 54 1C 8D 65 40 DD 45 EC F9 12 25 A0 59
libssh2_sftp_init()!
libssh2_sftp_open()!
libssh2_sftp_open() is done, now send data!
all done

High cpu usage !!!
 PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 2561 root 25 0 4804 1464 1244 R 99.3 0.1 0:09.71 lt-sftp_write_non_block

RedHat Enterprise Linux Server 5.1. But, I tested this scenario on 3 platforms. Same effect.
So, I think won't be a big problem to reproduce this issue on any Linux platform.

Please, confirm.

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Received on 2009-07-10