[squid-users] High utilization of CPU squid-3.5.23, squid-3.5.24

[Garri Djavadyan]

On Wed, 2017-02-01 at 23:55 +0300, Vitaly Lavrov wrote:
> Periodically squid begins to linearly increase the use of the CPU.
> Sometimes this process reaches 100%. At random moment of time the CPU
> usage is reduced to 5-15%,
> and in the presence of client requests can again start linearly
> increasing use of CPU.
> 
> In the protocols are no error messages.
> 
> CPU consumption does not correlate with the number of requests and
> traffic.
> 
> The increase CPU consumption from 0 to 60% occurs in about 4-5 hours,
> and to 100% for 6-8 hours.
> 
> A typical graph of CPU usage can be viewed on http://devel.aanet.ru/t
> mp/squid-cpu-x.png
> 
> With the "perf record -p` pgrep -f squid-1` - sleep 30" I have
> received the following information:
> 
> At 100% CPU load most of the time took 3 calls
> 
>   49.15% squid squid [.] MemObject :: dump
>   25.11% squid squid [.] Mem_hdr :: freeDataUpto
>   20.03% squid squid [.] Mem_hdr :: copy
> 
> When loading CPU 30-60% most of the time took 3 calls
> 
>   37.26% squid squid [.] Mem_node :: dataRange
>   22.61% squid squid [.] Mem_hdr :: NodeCompare
>   17.31% squid squid [.] Mem_hdr :: freeDataUpto
> 
> What is it ? Is it possible to somehow fix it?
> 
> System: slackware64 14.2
> 
> sslbump not used. http only.
> 
> Part of config:
> 
> memory_pools off
> memory_pools_limit 512 MB
> cache_mem 768 MB
> maximum_object_size_in_memory 64 KB
> cache_dir ufs           /cache/sq_c1 16312 16 256
> cache_dir ufs           /cache/sq_c2 16312 16 256
> cache_dir ufs           /cache/sq_c3 16312 16 256


Hi Vitaly,

It seems you faced known issue related to linear search through in-
memory nodes. See bug report 4477 [1].

[1] http://bugs.squid-cache.org/show_bug.cgi?id=4477


Garri