Good day time!
We've noticed the following issue with Samba 3.0.1 on Linux. When SMB client
asks for the first time on FID for a locking or read request on an opened
file, it causes an ACK to be sent from client side. Windows server also
requests ACK BUT much more rarely.
Sending ACK causes additional overhead when working in heavy locking and
unlocking environment. Windows server doesn't requests ACK to each new
request. Possibly it is not Samba's internals but how to get rid of this
ACK?
Possibly we can use some additional socket options? Here are the options in
smb.conf:
socket options = IPTOS_LOWDELAY TCP_NODELAY
kernel oplocks = no
posix locking = yes
blocking locks = yes
share modes = yes
locking = yes
oplocks = no
level2 oplocks = no
nt acl support = yes
Thank you.
Here is the dump:
Small description - Frame 94415 is a Read request, Frame 94417 is a Read
response which causes ACK to be sent in Frame 94418.
Frame 94415 (118 bytes on wire, 118 bytes captured)
Arrival Time: Feb 10, 2004 14:55:08.279799000
Time delta from previous packet: 0.000045000 seconds
Time since reference or first frame: 12.970217000 seconds
Frame Number: 94415
Packet Length: 118 bytes
Capture Length: 118 bytes
Ethernet II, Src: 00:a0:c9:69:01:36, Dst: 00:02:b3:52:13:73
Destination: 00:02:b3:52:13:73 (Intel_52:13:73)
Source: 00:a0:c9:69:01:36 (Intel-Hf_69:01:36)
Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.0.14 (192.168.0.14), Dst Addr:
192.168.0.101 (192.168.0.101)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 104
Identification: 0x1fdd (8157)
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: TCP (0x06)
Header checksum: 0x58ef (correct)
Source: 192.168.0.14 (192.168.0.14)
Destination: 192.168.0.101 (192.168.0.101)
Transmission Control Protocol, Src Port: 2720 (2720), Dst Port: nbsession
(139), Seq: 3036203, Ack: 3647740, Len: 64
Source port: 2720 (2720)
Destination port: nbsession (139)
Sequence number: 3036203
Next sequence number: 3036267
Acknowledgement number: 3647740
Header length: 20 bytes
Flags: 0x0018 (PSH, ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 1... = Push: Set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 8266
Checksum: 0x7cc5 (correct)
NetBIOS Session Service
Message Type: Session message
Flags: 0x00
.... ...0 = Add 0 to length
Length: 60
SMB (Server Message Block Protocol)
SMB Header
Server Component: SMB
Response in: 94417
SMB Command: Read AndX (0x2e)
Error Class: Success (0x00)
Reserved: 00
Error Code: No Error
Flags: 0x18
0... .... = Request/Response: Message is a request to the server
.0.. .... = Notify: Notify client only on open
..0. .... = Oplocks: OpLock not requested/granted
...1 .... = Canonicalized Pathnames: Pathnames are canonicalized
.... 1... = Case Sensitivity: Path names are caseless
.... ..0. = Receive Buffer Posted: Receive buffer has not been
posted
.... ...0 = Lock and Read: Lock&Read, Write&Unlock are not
supported
Flags2: 0x8000
1... .... .... .... = Unicode Strings: Strings are Unicode
.0.. .... .... .... = Error Code Type: Error codes are DOS error
codes
..0. .... .... .... = Execute-only Reads: Don't permit reads if
execute-only
...0 .... .... .... = Dfs: Don't resolve pathnames with Dfs
.... 0... .... .... = Extended Security Negotiation: Extended
security negotiation is not supported
.... .... .0.. .... = Long Names Used: Path names in request are
not long file names
.... .... .... .0.. = Security Signatures: Security signatures
are not supported
.... .... .... ..0. = Extended Attributes: Extended attributes
are not supported
.... .... .... ...0 = Long Names Allowed: Long file names are
not allowed in the response
Process ID High: 0
Signature: 0000000000000000
Reserved: 0000
Tree ID: 2
Process ID: 51966
User ID: 100
Multiplex ID: 58498
Read AndX Request (0x2e)
Word Count (WCT): 12
AndXCommand: No further commands (0xff)
Reserved: 00
AndXOffset: 0
FID: 0x21df
Offset: 0
Max Count Low: 16
Min Count: 16
Remaining: 16
High Offset: 0
Byte Count (BCC): 0
Frame 94417 (133 bytes on wire, 133 bytes captured)
Arrival Time: Feb 10, 2004 14:55:08.279891000
Time delta from previous packet: 0.000040000 seconds
Time since reference or first frame: 12.970309000 seconds
Frame Number: 94417
Packet Length: 133 bytes
Capture Length: 133 bytes
Ethernet II, Src: 00:02:b3:52:13:73, Dst: 00:a0:c9:69:01:36
Destination: 00:a0:c9:69:01:36 (Intel-Hf_69:01:36)
Source: 00:02:b3:52:13:73 (Intel_52:13:73)
Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.0.101 (192.168.0.101), Dst Addr:
192.168.0.14 (192.168.0.14)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 119
Identification: 0x8566 (34150)
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 64
Protocol: TCP (0x06)
Header checksum: 0x3357 (correct)
Source: 192.168.0.101 (192.168.0.101)
Destination: 192.168.0.14 (192.168.0.14)
Transmission Control Protocol, Src Port: nbsession (139), Dst Port: 2720
(2720), Seq: 3647783, Ack: 3036267, Len: 79
Source port: nbsession (139)
Destination port: 2720 (2720)
Sequence number: 3647783
Next sequence number: 3647862
Acknowledgement number: 3036267
Header length: 20 bytes
Flags: 0x0018 (PSH, ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 1... = Push: Set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 20162
Checksum: 0x99ef (correct)
NetBIOS Session Service
Message Type: Session message
Flags: 0x00
.... ...0 = Add 0 to length
Length: 75
SMB (Server Message Block Protocol)
SMB Header
Server Component: SMB
Response to: 94415
Time from request: 0.000092000 seconds
SMB Command: Read AndX (0x2e)
NT Status: STATUS_SUCCESS (0x00000000)
Flags: 0x88
1... .... = Request/Response: Message is a response to the
client/redirector
.0.. .... = Notify: Notify client only on open
..0. .... = Oplocks: OpLock not requested/granted
...0 .... = Canonicalized Pathnames: Pathnames are not
canonicalized
.... 1... = Case Sensitivity: Path names are caseless
.... ..0. = Receive Buffer Posted: Receive buffer has not been
posted
.... ...0 = Lock and Read: Lock&Read, Write&Unlock are not
supported
Flags2: 0xc801
1... .... .... .... = Unicode Strings: Strings are Unicode
.1.. .... .... .... = Error Code Type: Error codes are NT error
codes
..0. .... .... .... = Execute-only Reads: Don't permit reads if
execute-only
...0 .... .... .... = Dfs: Don't resolve pathnames with Dfs
.... 1... .... .... = Extended Security Negotiation: Extended
security negotiation is supported
.... .... .0.. .... = Long Names Used: Path names in request are
not long file names
.... .... .... .0.. = Security Signatures: Security signatures
are not supported
.... .... .... ..0. = Extended Attributes: Extended attributes
are not supported
.... .... .... ...1 = Long Names Allowed: Long file names are
allowed in the response
Process ID High: 0
Signature: 0000000000000000
Reserved: 0000
Tree ID: 2
Process ID: 51966
User ID: 100
Multiplex ID: 58498
Read AndX Response (0x2e)
Word Count (WCT): 12
AndXCommand: No further commands (0xff)
Reserved: 00
AndXOffset: 0
FID: 0x21df
Remaining: 65535
Data Compaction Mode: 0
Reserved: 0000
Data Length Low: 16
Data Offset: 59
Data Length High (multiply with 64K): 0
Reserved: 000000000000
Byte Count (BCC): 16
File Data: 0044000000000000B200008F0A00E000
Frame 94418 (54 bytes on wire, 54 bytes captured)
Arrival Time: Feb 10, 2004 14:55:08.279905000
Time delta from previous packet: 0.000014000 seconds
Time since reference or first frame: 12.970323000 seconds
Frame Number: 94418
Packet Length: 54 bytes
Capture Length: 54 bytes
Ethernet II, Src: 00:a0:c9:69:01:36, Dst: 00:02:b3:52:13:73
Destination: 00:02:b3:52:13:73 (Intel_52:13:73)
Source: 00:a0:c9:69:01:36 (Intel-Hf_69:01:36)
Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.0.14 (192.168.0.14), Dst Addr:
192.168.0.101 (192.168.0.101)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 40
Identification: 0x20dd (8413)
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: TCP (0x06)
Header checksum: 0x582f (correct)
Source: 192.168.0.14 (192.168.0.14)
Destination: 192.168.0.101 (192.168.0.101)
Transmission Control Protocol, Src Port: 2720 (2720), Dst Port: nbsession
(139), Seq: 3036267, Ack: 3647862, Len: 0
Source port: 2720 (2720)
Destination port: nbsession (139)
Sequence number: 3036267
Acknowledgement number: 3647862
Header length: 20 bytes
Flags: 0x0010 (ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 0... = Push: Not set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 8144
Checksum: 0x0fc2 (correct)
SEQ/ACK analysis
This is an ACK to the segment in frame: 94417
The RTT to ACK the segment was: 0.000014000 seconds
