Hello! On Mon, Oct 02, 2017 at 11:51:33PM -0400, rnmx18 wrote:
> Hi, > > We are trying to use NGINX for caching service in low bandwidth, high > latency mobile networks. The service is to stream 10-sec video segments of > different types ranging from 2MB to 50MB. > > NGINX proxy_buffering configuration is as follows: > > proxy_buffering on; > proxy_buffer_size 4k; > proxy_buffers 64 4k; > proxy_busy_buffers_size 128k; > proxy_temp_file_write_size 64k; > > The slow clients results in NGINX buffering of the response and writing data > to disk as part of temporary buffering. The disk IO is causing higher TTFB > and higher load time for video download. > > We have tried to configure the proxy_max_temp_file_size to 0 to disable the > buffering. This change results in interrupts not being balanced as shown > below in the top command output - core0 and core15 is using 100%. > > top - 13:53:04 up 6 days, 2:31, 5 users, load average: 6.42, 4.35, 3.84 > Tasks: 370 total, 6 running, 364 sleeping, 0 stopped, 0 zombie > %Cpu0 : 0.0 us, 0.0 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi,100.0 si, 0.0 > st [...] > Couple of queries: > a) Why do we get unbalanced interrupts when buffering is disabled? Try looking on what runs on these CPUs. Given that it's "100.0 si", I would suggest that it is your NIC interrupt threads trying to cope with load. > b) How to configure NGINX to throttle the upstream read and avoid temp > buffering? With proxy_max_temp_file_size set to 0 nginx won't buffer anything to disk, and will read from upstream up to available proxy_buffers. As long as configured buffers are full, nginx will stop reading from the upstream server till at least one buffer is free. That is, nginx will read from the upstream at a rate controlled by bandwidth of connected clients. You can use normal client limiting mechanisms such as limit_rate and limit_conn if the rate observed is too high. Additionly, the proxy_limit_rate directive can be used to control rate limiting of connections to upstream servers, see http://nginx.org/r/proxy_limit_rate. Though this is primary useful when you don't disable disk buffering but rather have to keep it enabled, for example, when using cache. -- Maxim Dounin http://nginx.org/ _______________________________________________ nginx mailing list nginx@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx
