Suggestions to increase throughput on WLAN with WRT54GS v7?
I recently upgraded to 10Mbps DSL. Wired directly to the modem, I get 10Mbps, wired directly to the linksys, I get 10Mbps, connected wirelessly, I get 7Mbps. My wireless connection shows between 85-100% all the time for signal from my router. It shows I connect at 54Mbps to the router. The firmware is the latest for the router model. Pings to anything have good response time and no lost packets so it doesn't appear to be a latency issue. I've narrowed it down to the wireless, because with file transfers between my 2 computers that are wireless I get between 7-9Mbps. I live in an apartment complex and there are 8 other wireless networks I can detect. My only thought is that with all those wireless devices flooding traffic, the router must have to look at and discard each packet that isn't meant for it, which takes up it's ability to process and slows down the throughput. Any suggestions on things to try that could squeeze that last 3M out? Also, the router and computers are only about 20-25 feet apart and have direct line of sight.
Try various channels like 1,11,9 etc and there might be some channel with minimum disturbance from other wireless networks. Also try changing advanced wireless settings: set beacon interval to 50, fragmentation and RTS threshold to 2306 and DTIM to 2.
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When typing the name of the contact I want to send a text message to, names from my contact list no longer pop up as suggestions. Can anyone help me with this?
There's always a way to reset the device jmn33! Thanks for keeping us in the loop. To process a full reset/restore on the device please visit http://vz.to/12TLCsR. Please keep us posted once this is completed, thanks!
MatthewS_VZW
Follow us on Twitter @VZWSUPPORT -
Please suggest a select query / sub query with out using any subprograms or
source table: Three columns ORIGIN, DESTINATION,MILES
Origin Destination Miles
Sydney Melbourne 1000
Perth Adelaide 3000
Canberra Melbounre 700
Melbourne Sydney 1000
Brisbane Sydney 1000
Perth Darwin 4000
Sydney Brisbane 1000
out put :Three columns ORIGIN, DESTINATION,MILES
Duplicate routes are to be ignored so the output is
Origin Destination Miles
Sydney Melbourne 1000
Perth Adelaide 3000
Canberra Melbounre 700
Brisbane Sydney 1000
Perth Darwin 4000
Please suggest a select query / sub query with out using any subprograms or functions/pkgs to get the out put table.Hi,
user9368047 wrote:
... Please suggest a select query / sub query with out using any subprograms or functions/pkgs to get the out put table.Why? If the most efficient way to get the results you want involves using a function, why wouldn't you use it?
Here's one way, without any functions:
SELECT a.*
FROM source_table a
LEFT OUTER JOIN source_table b ON a.origin = b.destination
AND a.destination = b.origin
AND a.miles = b.miles
WHERE b.origin > a.origin -- Not b.origin > b.origin
OR b.origin IS NULL
;If you'd care to post CREATE TABLE and INSERT statements for your sample data, then I could test this.
Edited by: Frank Kulash on Nov 6, 2012 7:39 PM
Corrected WHERE clause after MLVrown (below) -
Hi!
Since the sw upgrade to version 7.3.101.0 (wlc 5508) i have the following issue.
We have a WLAN with 802.1x (WPA2/AES) secured. Before the update the users need to enter user/ pw every time when they reconnect (WLAN switch off/ on again) to the WLAN.
Now the users don`t need to enter user/ pw when they reconnect to the WLAN.
I could not find any setting on wlc to clear this issue.
Thank you for your help!So i think there is now way, because the client devices are not managed (e.g. smartphones).
What i try is this setup:
Layer 2 Security:
WPA+WPA2
WPA2 Policy
AES
Authentication Key Management set to 802.1x
Layer 3 Security:
Web Policy/ Splash Page
...connection is working, but user don`t need to re enter credentials after reconnect (ipad; galaxy 3..) -
There's no agree button on the new iTunes terms and conditions, so I can't buy any apps for my iPhone5, with iOS7. Any suggestions? Three E-mail exchanges with Apple didn't help,can you?
Yes me too, tried re setting and enabling changes but no agree button anywhere?
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Pls help me.i have a problem with WRT54G wireless router.
Dear all, Now i got face some problem with WRT54G wireless router.The problem is after i connect to the internet...the wireless will automatic drop..is that any ppl here got face this and got any solution to solve it...?thanks for sharing..
hi...logon to router's setup page and try changing channel to 11, go to advanced wireless settings, try changing transmission rate to 54Mbps, beacon interval to 50, fragmentation and RTS threshold to 2304, also try upgrading latest firmwar on the router...check whether it maks any difference or not and let me know.
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No auto-connect to WLAN with hidden SSID
I work in Infrastructure Services at the IBM Zurich Research Laboratory.
Across IBM, there is a standard setup for wireless LAN access. There’s a public WLAN that provides access only to the internet; and there’s a private WLAN that provides access to both the internet and the corporate intranet. The private WLAN requires authentication via WPA/WPA2 Enterprise using LEAP or a certificate, and has a hidden SSID.
Both WLANs are served by the same access points.
The iPhone and iPod Touch do not automatically reconnect to the private WLAN with the hidden SSID.
Each time the iPhone wakes from sleep, the user must connect manually to the private WLAN. The user must go into Settings and then Wi-Fi, wait for the private WLAN to appear in the list (there’s always a delay) and then tap on it. Also, if one opens Mail or Safari application before connecting manually, the the blue pop-up list of available networks will not include the private WLAN with the hidden SSID.
This is a major inconvenience, because it adds half a minute or more to each operation that requires network access. Checking one’s email—something that should normally take no more than ten seconds—instead takes a minute or more, depending on how quickly one manages to connect.
This bug also results in needless expense, because network operations that should go over the local WLAN often go instead over the mobile phone network.
The inability of the iPhone/iPod Touch to reconnect automatically to networks with hidden SSID has been a problem since the original iPhone came out.
This problem is an obstacle preventing wider adoption of the iPhone within IBM.Anyone have an update on this ?
I have a new 3GS with 3.1.2 and have the same issue. I haven't tried the factory reset yet, but from this link;
http://l00pback.wordpress.com/2009/10/14/iphone-3-1-bug-no-auto-reconnect-to-hid den-ssid-wireless-networks/
“Work around”: Not really a workaround, but a sightly less frustrating way of reconnecting… when in range of the network… recreate the network by entering the SSID and leave out any of the security stuff then click Join. The join will fail (for obvious reasons), but will then “remind” the phone that that network exists and will then connect using the previously configured settings."
takes some of the pain away. -
3850. mac filter at wlan with wpa key
Hello
I want to get simple mac filter at certain WLAN with psk authentication
I have such at my home cisco881 - MAC-based ACL apply to the radio interface.
I don't find how to make MAC-based ACL at 3850.
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How to integrate a Laserprinter into a WLAN with multiple Aiport Stations?
Hello,
I set up a WLAN with multiple Airport Stations in my house like this:
Time Capsule is the main station (placed in second floor) which creates the WLAN and is connected via Ethernet to the ADSL router of my internet connection provider. Works fine and stable.
Secondly I placed an AirPort Extreme station in our first floor to extend the WLAN of the main station. Without that second station I had bad connection in first floor.
Now I wanted to integrate my Laserprinter to that WLAN so that every device could use it. The problem is, that I cannot place the printer in the second floor where the main station (Time Capsule) is located. Therefore I placed the printer in the first floor next to the second station and connected them via ethernet. I gave the printer a unique IP (10.0.0.200) which will never be used by another device (I set DHCP IP range of Time Capsule from 10.0.1.2 to 10.0.1.200).
But connection to the printer fails
So, my question: is it possible to connect a ethernet laserprinter to that network via the second station or must it be always connected to the main station?i fixed the problem by my own. Topic can be closed
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Nilsene,
perhaps your hard drive already has that firmware version installed? That could explain why you’re getting the “this update is not necessary for your computer” pop-up.
Are you making regular backups of your hard drive? Its increasing volume might be an early warning of an approaching disk failure, so if you’re not already doing so, I’d highly recommend purchasing an external disk for use as a Time Machine backup destination — that way, in case of a sudden failure, you won’t permanently lose all of your personal files. -
I have set up VPN between two WLANs both using WRT54G routers.
Take a look at the write-up and the screenshots.
wlwhere are the write up and screen shots???
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No WLan Connectivity when Lan used with WRT54G
I have a desktop-PC (Win XP-SP2) connected to Lan-port 1 on the WRT54G (v8.00.2)
Every time the PC is on (even at boot prompt) I cannot connect any laptop (win or Linux) via WLan. If a WLan connention is already established when is PC is started, then the connection fails immediately, the network is no more visible in the available network list.
I searched the net as well as this forum and found some aparently similar problems, but never a solution.
Can anyone help, please?Try connecting the different PC to the router hard-wired and check if you are getting the same problem...? If you do not get the same problem then,try to update the driver of the NIC(wired ethernet adapter) on your computer.
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Need help increasing throughput
Hello,
My application is a message processing system. I needs a tranasaction througput of 10000 msgs/sec. Now since I also needed the durability of data, I decided to go ahead with TDS in bdb. I am facing couple of problems. I start off with giving you a background of the environmental and db settings I am using.
DbEnv has been opened (along with all the vanilla options for txn opening) with AUTO_COMMIT.
DBENV->cache size has been set to 5mb
DBENV->logbuffer size has been set to 2mb
(the above 2 in DB_CONFIG file)
DB has been opened with AUTO_COMMIT and DB_NODUP (doesn't enternatin any dupe msgs)
1. I need to write each msg that comes as input into the db for future reference. That means since my input data is coming to me at 10000 msgs/sec I am doing a DB->put and hence a txn commit ( I am currently using autocommit flag) 15000 times a sec. And as a consequence of the commit, I am flushing logs to the disk 15000 times in a sec and thats like huge huge performance penalty. This gave me a msg rate of 350 msgs/sec
2. I tried to resolve pt 1 by using non durable txn with the help of DB_TXN_NO_SYNC flag. This has helped a lot in increasing the throughput which is nice. Its now upto 5500 msgs/sec. Though not any way near to my requirement but a definite indication that its the right direction. But I do need to ensure relative durabilitiy. We can afford to lose 1 sec of data but nothing more.
3. I tried to resolve pt 2 by calling memp_sync() and log_flush() every sec in an independent thread. Now this is not working as i hoped. Whats happenign is that though the DB is now unable to find the msgs that I have entered before (I am using DB->get) method. Am I going wrong somewhere? Also I need to know what does logs_flush actually do, does it flush the log buffer onto the log files on disk? Does it take care that if we are using that log buffer for reads or something, meaning its active, does it wait? What happens if there is a crash while my thread is using the logs_flush method ? would log files get corrupted ?
4. What would be your suggestion in terms of incresing my thoruhgput? How can I use memp_trickle ? Would that be more appropriate here?Hi Nishith,
Can you try setting the DB_REGION_INIT flag on the
environment before opening it? From your description
and the stack trace, it looks like the slow startup
is caused by page faults in shared regions.
You are correct. Once I set the DB_REGION_INIT flag, the opening rush of data is handled like a charm. Our app has stopped queuing at the onset.
On the issue of calling time(3), I haven't struck
this before. Short of editing the source code (in
txn/txn.c) by hand, there is no easy way to avoid
those calls. Out of interest, how many time() calls
can you make in a second on your box?The system call profiler shows ( glance on hpux) that time is being called on an average 3500 times a sec, in fact its proportional the msgs/sec we are flowing which is at these rates 2500 msgs/sec. But since we cannot do much abotu it, I am goign to ignore the same for a while.
I wanted to explain the second bottleneck we are facing:
Whats happening is that once we start a process, we keep increasing the msg rate uptill 2000. Between 2000 - 2500 msgs/sec, I see that the performance starts deteriorating and our application starts queing. Such that even if we reduce the msg rates to 2000 msg/sec, the application keeps on queing. Allow me to inform you that no system limit has been hit at this point, cpu is available, memory is available. IO is bad though. . Call stack at this point showed us these results occasionally:
2.5 2.5 0.0 libc.so.1::__fsync_sys [47]
libc.so.1::fdatasync [46]
hslapp::__os_fsync [45]
hslapp::__log_flush_int [39]
hslapp::__log_flush [41]
hslapp::__memp_pgwrite [31]
hslapp::__memp_bhwrite [32]
hslapp::__memp_alloc [33]
hslapp::__memp_fget [12]
hslapp::__bam_search [14]
hslapp::__bam_c_search [13]
hslapp::__bam_c_put [22]
hslapp::__db_c_put [21]
hslapp::__db_put [20]
hslapp::__db_put_pp [10]
hslapp::Db::put(DbTxn*,Dbt*,Dbt*,unsigned int) [11]
hslapp::CtsTradesByTimeDb::writeRecord
2.5 2.5 0.0 libc.so.1::__fsync_sys [47]
libc.so.1::fdatasync [46]
hslapp::__os_fsync [45]
hslapp::__log_flush_int [39]
hslapp::__log_flush [41]
hslapp::__memp_pgwrite [31]
hslapp::__memp_bhwrite [32]
hslapp::__memp_alloc [33]
hslapp::__memp_fget [12]
hslapp::__bam_search [14]
hslapp::__bam_c_search [13]
hslapp::__bam_c_get [43]
hslapp::__db_c_get [40]
hslapp::__db_get [38]
hslapp::__db_get_pp [37]
hslapp::Db::get(DbTxn*,Dbt*,Dbt*,unsigned int) [36]
hslapp::CtsTradesByRrnDb::isDup
Flat profile of functions showed these:
2.72 14.93 6369 libc.so.1::T_19_72f2_cl___doprnt_main doprnt.c
2.40 17.33 5607 hslapp::__db_pthread_mutex_lock mut_pthread.c
2.24 19.57 5247 hslapp::__bam_cmp bt_compare.c
1.96 21.54 4593 hslapp::__memp_fget mp_fget.c
1.91 23.45 4472 libc.so.1::real_malloc malloc.c
1.78 25.22 4153 libc.so.1::memmove
1.49 26.71 3480 hslapp::__bam_search bt_search.c
1.20 27.91 2817 hslapp::__db_pthread_mutex_unlock mut_pthread.c
1.17 29.08 2728 hslapp::__bam_defcmp bt_compare.c
1.12 30.20 2628 hslapp::__lock_get_internal lock.c
The question is 1. Why is a Db->get ( a read call ) calling a fsync - a flush of the os buffers??? now thats a huge performance hit right there.
2. Why Db->put is callnig a fsync since I have set the dbenv->DB_txn_no_sync. These statements seem to counter each other?
At this time on the system there is hardly any cpu pressure, nor memory pressure and once again our main thread starts getting blocked on system calls. Sometimes as high as 30%. On further observation also noted that at this time the disk utilization of the app more than doubles. From around 20% - 56-45 %, it continues to remain in this state throughout the testing then and hence the performance goes down horribly.
msg processing is not smooth, sometimes app is able to process 1400 msgs./sec, the very next update(interval 3 secs), its processinga rate of 2400 msg.sec,. The db configuration highlights ares as follows:
DB_NO_TXN_SYNC, DB_REGION_INIT, DB_THREAD have been set along with the necessary flags for opening a transaction environment. Currently txn_checkpoint is being run every 5 secs. I am not using memp_sync || memp_tricle cos I figured that every 5 seconds ckpting thread would do the same thing. Cache is set at 32 mb, log buffer size is set at 8mb. page size at 32k (fs block siz 8k). Currently acording to db_stat -m am getting a 99%page hit. I have 2 dbs. Record size that would get written / msg is 100 bytes for db 1 and 50 bytes / msg for db2 respectively.
Am i doing something incorrect, which is causing this sort of a performance degradation. The ques seem to go up and then come down and the cycle repeats.
Moreso i have these general queries all linked to trying to solve or get an alternative soln to the above mentioned problems
1. How can I find out the log record size on ech txn commit? This will help me to tune ckpting more finely? maybe based on size rather on time.
2. You suggested in your first reply to me that I may use DB_TXN_WRITE_NOSYNC, my understanding of this flag is that it will write the dirty pages to the system cahce buffer immediately and it does not flush the logs. So if I do have a log buffer of 8mb it will not flush as long as the 8 mb doesnt get fully filled up with log records. So I surely may have to reconfigure the same. So definitely i need to have an answer for query no 1. (size of log recs). so lets say 512k which means every 1000 msgs the log buffer would get filled up and it would flush. This may not be in sync with when the os flushes the dirty pages from its cache to disk. Would it create recoverability problems. After having done all that we still need to run the ckpt thread to ensure low recoverability time in case of crash. Is my understanding of this process correct.
3. If we have 2 db, each ahving different sizes of key-data paireach of these dbs would have their own alloted set of pages, so when we decide the cache size its applicable to all db under that environment correct? So that means it would be equally divided or how would the memory management take place?
If you need any more inputs about the app from me, please feel free to ask.
Regards,
Nishith.
Regards,
Michael Cahill, Oracle. -
Suggestion in increasing the SGA and PGA after increase in the RAm of the machine .
Hi All,
Need an expert suggestion on the change's in the SGA and PGA of the oracle database after increasing the size of the machines RAM .
We have 64G of RAM in the machine .
There are 9 DB's running on oracle 10g and 11g on this machine
The total SGA of all the database's is around 18G .
DB1 has 2G of MAX_SGA_SIZE
DB2 has 8G of MAX_SGA_SIZE
DB3 has 1G of MAX_SGA_SIZE
DB4 has 2G of MAX_SGA_SIZE
DB5 has 676M of MAX_SGA_SIZE
DB6 has 1.5G of MAX_SGA_SIZE
DB7 has 1.2 G of MAX_SGA_SIZE
DB8 has 675M of MAX_SGA_SIZE
DB9 has 672 M of MAX_SGA_SIZE
Now the machine RAM is up to 96G 64+ 32
what would be the suggestion on the increase in the SGA and PGA max size .
Any expert suggestion is highly apprciated .
Thanks in AdvanceThanks for this Justin.
Here the exercise is to add 4 CPU's and 32G RAM to the server earlier it was with 4 CPU's and 64G RAM this was decided by the server support team .
here is the stats from SAR command ..
The platform is
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
CORE 11.2.0.2.0 Production
TNS for Linux: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production
04:00:01 CPU %user %nice %system %iowait %steal %idle
04:10:02 all 86.47 0.00 12.52 0.99 0.00 0.02
04:20:01 all 84.83 0.01 11.80 3.21 0.00 0.15
04:30:01 all 76.23 0.00 10.30 12.34 0.00 1.12
04:40:01 all 79.14 0.00 12.07 8.30 0.00 0.49
04:50:01 all 77.63 0.00 12.19 9.40 0.00 0.77
05:01:01 all 75.95 0.00 10.50 12.80 0.00 0.75
05:11:01 all 83.21 0.00 11.98 4.54 0.00 0.26
05:21:01 all 76.37 0.01 11.20 11.49 0.00 0.94
05:31:01 all 77.97 0.00 9.04 10.30 0.00 2.69
Average: all 79.72 0.00 11.28 8.20 0.00 0.80
Now that the 4 CPU's and RAM is been added , my request is how to calculate the required kernal parameters for oracle to this new configuration for some improvement in the oracle performance .
like kernal.shmmax
kernal.shmall
/dev/shm file system
largest value of MEMORY_MAX_TARGET or MEMORY_TARGET of all instances
the oracle is set as automatic memory management . it is not an RAC environment .
Any Expert suggestion is highly apprciated .
Thanks in advance .
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