# Slow GUI in GRC **URL:** \ **Category:** GNU Radio\ **Created:** [December 31, 2014, 5:19pm UTC](https://www.ruby-forum.com/t/slow-gui-in-grc/233651 "2014-12-31T17:19:01Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [December 31, 2014, 5:19pm UTC](https://www.ruby-forum.com/t/slow-gui-in-grc/233651/1 "2014-12-31T17:19:01Z")
Hi, We recently bought a new machine with like 4 GHz processor, 16 GB of RAM. For the graphic card, we use the Radeon R7 250 1000 MHz GDDR5. Latest version of Ubuntu (14.04 LTS) was installed along with GNU Radio built from the source. Everything seems to be installed just fine. However, when trying to use GNU Radio Companion (GRC), the GUI’s are so slow. Every time I try to place in or move the blocks in GRC, the whole GUI stuck for a while and it gets so slow. Because of this, I am not able to run GRC. Prior to this, GRC used to work just fine on another machine with a much lower specs for the RAM and the processor but with RS880 [Radeon HD 4200] graphic card. What is the cause for this problem and how to fix it? Could it be the new graphic card (Radeon R7 250 GDDR5)? Thank you. Best regards, Khalid ---
**Author:** ![khalide](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/3bc359/32.png) [@khalide](https://www.ruby-forum.com/u/khalide)\ **Post date:** [January 5, 2015, 4:43pm UTC](https://www.ruby-forum.com/t/slow-gui-in-grc/233651/2 "2015-01-05T16:43:12Z")
On Wed, Dec 31, 2014 at 11:17 AM, khalid.el-darymli \< [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)\> wrote: > Best regards, > Khalid Sorry, this sounds like a computer/os/configuration problem on your end. There were some slowdown issues with GRC that were patched a while ago, so if you’ve built from the latest source, things shouldn’t be that bad. Tom ---
**Author:** ![khalide](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/3bc359/32.png) [@khalide](https://www.ruby-forum.com/u/khalide)\ **Post date:** [January 5, 2015, 4:56pm UTC](https://www.ruby-forum.com/t/slow-gui-in-grc/233651/3 "2015-01-05T16:56:51Z")
On 01/05/2015 10:41 AM, Tom R. wrote: > ``` > fine. However, when trying to use GNU Radio Companion (GRC), the > What is the cause for this problem and how to fix it? Could it be > > ``` > > while ago, so if you’ve built from the latest source, things shouldn’t > be that bad. > > Tom I’ve noticed that for some graphics cards, some OS will revert to using the FB driver for a card, which is quite slow, since _all_ rendering is done in software. ---
**Author:** ![khalide](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/3bc359/32.png) [@khalide](https://www.ruby-forum.com/u/khalide)\ **Post date:** [January 5, 2015, 5:34pm UTC](https://www.ruby-forum.com/t/slow-gui-in-grc/233651/4 "2015-01-05T17:34:05Z")
Khalid, It would be much easier to respond to these and for searching in the archives later if you posted these in new and separate threads. Thanks, Tom On Mon, Jan 5, 2015 at 11:25 AM, khalid.el-darymli \ **Author:** ![khalide](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/3bc359/32.png) [@khalide](https://www.ruby-forum.com/u/khalide)\ **Post date:** [January 5, 2015, 5:27pm UTC](https://www.ruby-forum.com/t/slow-gui-in-grc/233651/5 "2015-01-05T17:27:15Z") Thanks very much Tom for your response. This issue is resolved after replacing the graphic card driver installed by default with that provided from the website of the card developer. However, I am having two other issues now. One, in the terminal, I am occasionally getting capital U’s and L’s when running GNU Radio with one Tx and 4 Rx channels. Please note that I am using timed-commands to start both the Tx and Rx’s at the same time. When I check the system monitor while GNU Radio is running (please see the attachment), the CPU history and RAM usage seem to be fine. What causes this issue and how to handle it? Could it be due to some instability in the writing speed to the hard drive? BTW, I am having the same issue for my older PC (a PC with less specs). The System Monitor tells me that my CPU usage is around 60% and my RAM usage is around 25 %, however, I am getting U’s and L’s when I try to use four Rx channels. Please note that the system doesn’t throw lots of U’s and L’s at once, it is a kind of frequent where bunch of them are thrown out every few seconds or so. Two, although on my older machine I am able to use the’ virtual source’ and ‘virtual sink’ blocks without any problems, when I try to use them on the new PC, I get the following error: Traceback (most recent call last): File “./test\_skh.py”, line 595, in tb = test\_skh() File “./test\_skh.py”, line 486, in **init** self.connect((self.virtual\_source\_0, 0), (self.blocks\_multiply\_conjugate\_cc\_0, 0)) File “/usr/local/lib/python2.7/dist-packages/gnuradio/gr/hier\_block2.py”, line 93, in **getattr** return getattr(self.\_impl, name) _AttributeError: ‘top\_block\_sptr’ object has no attribute ‘virtual\_source\_0’_ Things work fine if I replace the virtual blocks with direct connections. I am not sure why? Thanks in advance for your help. Best regards, Khalid