Thanks a lot Steve, Paul, Anthm, John !<br><br>I will try both timerfd and the kernel freq thing :)<br><br>Btw, I am not using any T.38 or IP. Here is the set-up and config<br>
<br>
E1 &lt;-&gt; Sangoma A108D &lt;-&gt; libPRI &lt;-&gt; FreeTDM &lt;-&gt; mod_spandsp <br>
<br>
The Sangoma cards take their timing source from the E1, echo cancellation is disabled. <br>
<br>
There is no T.38 or any other IP. We are using G.711 only <br>
<br>
Kernel timing related info<br>
$grep CONFIG_HZ= /boot/config-`uname -r`<br>
CONFIG_HZ=100<br>
<br>
$ cat freetdm.conf <br>
<br>
[span wanpipe wp1]<br>
trunk_type =&gt; e1<br>
group=1<br>
b-channel =&gt; 1:1-15<br>
d-channel =&gt; 1:16<br>
b-channel =&gt; 1:17-31<br>
<br>
etc.<br>
<br>
$ cat /etc/wanpipe/wanpipe1.conf <br>
<br>
[devices]<br>
wanpipe1 = WAN_AFT_TE1, Comment<br>
<br>
[interfaces]<br>
w1g1 = wanpipe1, , TDM_VOICE_API, Comment<br>
<br>
[wanpipe1]<br>
CARD_TYPE     = AFT<br>
S514CPU     = A<br>
CommPort     = PRI<br>
AUTO_PCISLOT     = NO<br>
PCISLOT     = 6<br>
PCIBUS      = 1<br>
FE_MEDIA    = E1<br>
FE_LCODE    = HDB3<br>
FE_FRAME    = CRC4<br>
FE_LINE        = 1<br>
TE_CLOCK     = NORMAL<br>
TE_REF_CLOCK    = 0<br>
TE_SIG_MODE     = CCS<br>
TE_HIGHIMPEDANCE    = NO<br>
TE_RX_SLEVEL    = 430<br>
HW_RJ45_PORT_MAP = DEFAULT<br>
LBO         = 120OH<br>
FE_TXTRISTATE    = NO<br>
MTU         = 1500<br>
UDPPORT        = 9000<br>
TTL        = 255<br>
IGNORE_FRONT_END    = NO<br>
TDMV_SPAN        = 1<br>
TDMV_DCHAN        = 16<br>
TE_AIS_MAINTENANCE = NO                                #NO: defualt  YES: Start port in AIS Blue Alarm and keep line down<br>
                                                                             
 #wanpipemon -i w1g1 -c Ttx_ais_off to disable AIS maintenance mode<br>
                            
                                                  #wanpipemon -i w1g1 -c
 Ttx_ais_on to enable AIS maintenance mode  <br>
TDMV_HW_DTMF        = YES                                 # YES: receive dtmf events from hardware<br>
TDMV_HW_FAX_DETECT        = NO                       # YES: receive fax 1100hz events from hardware<br>
HWEC_OPERATION_MODE     = OCT_NORMAL     # OCT_NORMAL: echo cancelation enabled with nlp (default) <br>
                                    
                                         # OCT_SPEECH: improves software
 tone detection by disabling NLP (echo possible)<br>
                                    
                                         # OCT_NO_ECHO:disables echo 
cancelation but allows VQE/tone functions. <br>
HWEC_DTMF_REMOVAL       = NO                        # NO: default  YES: 
remove dtmf out of incoming media (must have hwdtmf enabled)<br>
HWEC_NOISE_REDUCTION    = NO                      # NO: default  YES: reduces noise on the line - could break fax<br>
HWEC_ACUSTIC_ECHO       = NO                         # NO: default  YES: enables acoustic echo cancellation<br>
HWEC_NLP_DISABLE        = NO                           # NO: default  YES: guarantees software tone detection (possible echo)   <br>
HWEC_TX_AUTO_GAIN       = 0                            # 0: disable   
-40-0: default tx audio level to be maintained (-20 default)<br>
HWEC_RX_AUTO_GAIN       = 0                            # 0: disable   
-40-0: default tx audio level to be maintained (-20 default)  <br>
HWEC_TX_GAIN            = 0                                  # 0: disable   -24-24: db values to be applied to tx signal<br>
HWEC_RX_GAIN            = 0                                  # 0: disable   -24-24: db values to be applied to tx signal<br>
<br>
[w1g1]<br>
ACTIVE_CH    = ALL<br>
TDMV_HWEC    = YES<br>
MTU         = 80<br>
<br>
<br>
$ cat autoload_configs/freetdm.conf.xml <br>
&lt;configuration name=&quot;freetdm.conf&quot; description=&quot;Freetdm Configuration&quot;&gt;<br>
  &lt;settings&gt;<br>
    &lt;param name=&quot;debug&quot; value=&quot;1&quot;/&gt;<br>
  &lt;/settings&gt;<br>
<br>
        &lt;config_profiles&gt;<br>
        <br>
        &lt;profile name=&quot;my_pri_te_1&quot;&gt;<br>
            &lt;param name=&quot;switchtype&quot; value=&quot;euroisdn&quot; /&gt;<br>
            &lt;param name=&quot;interface&quot; value=&quot;pri_cpe&quot;/&gt;<br>
        &lt;/profile&gt;<br>
        <br>
        &lt;/config_profiles&gt;<br>
    <br>
        <br>
    &lt;libpri_spans&gt;<br>
        <br>
        &lt;span name=&quot;wp1&quot; cfgprofile=&quot;my_pri_te_1&quot;&gt;<br>
                  &lt;param name=&quot;debug&quot; value=&quot;all&quot; /&gt;<br>
            &lt;param name=&quot;dialplan&quot; value=&quot;XML&quot;/&gt;<br>
            &lt;param name=&quot;context&quot; value=&quot;default&quot;/&gt;<br>
             &lt;param name=&quot;l1&quot; value=&quot;alaw&quot;/&gt;<br>
        &lt;/span&gt;<br>
<br>
etc.<br><br clear="all">regards,<br>Anita<br><br>
<br><br><div class="gmail_quote">On Fri, May 4, 2012 at 4:34 AM, John <span dir="ltr">&lt;<a href="mailto:freeswitch@earthspike.net" target="_blank">freeswitch@earthspike.net</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Ubuntu default timer for the server kernel is 100Hz (although I haven&#39;t<br>
checked 12.04).  You need the -preempt kernel for low latency and<br>
1000Hz.  It&#39;s easy to apt-get install; you then need to tweak the GRUB<br>
config to make it your default kernel on (re)boot.<br>
<span class="HOEnZb"><font color="#888888"><br>
John<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
On 03/05/12 16:19, Paul Cupis wrote:<br>
&gt; On Thu, May 03, 2012 at 05:53:01PM +0530, Anita Hall wrote:<br>
&gt;&gt;    No, I am running FreeSWITCH on an Ubuntu 64-bit Quad core machine.<br>
&gt;&gt;    There is no VM.<br>
&gt;&gt;    What all things should I check to ensure that the timing on my system<br>
&gt;&gt;    is good? Like, may be, my motherboard is bad or my kernel could be<br>
&gt;&gt;    tuned better ?<br>
&gt; The most common suggestion is to use a kernel with 1000Hz timer. I think<br>
&gt; that the default timer for Ubuntu is 250, so this would be first thing<br>
&gt; to check/change.<br>
&gt;<br>
&gt; You can check by running:<br>
&gt;<br>
&gt;      grep CONFIG_HZ= /boot/config-`uname -r`<br>
&gt;<br>
&gt; and if it is not 1000, it would be worth installing a 1000Hz kernel<br>
&gt; and re-testing.<br>
&gt;<br>
&gt; Ubuntu may have a packages -lowlatency kernel which has a 1000Hz timer<br>
&gt; but this will also have other changes. I think a lot of people will<br>
&gt; compile a custom kernel based on the standard Ubuntu one, just changing<br>
&gt; that one configuration option.<br>
&gt;<br>
&gt; Regards,<br>
&gt;<br>
&gt;<br>
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