Hi Bryan, Thanks for your reply! I checked my server and I found it is already a small value.
$ sudo sysctl -a | grep vm.dirty_writeback_centisecs vm.dirty_writeback_centisecs = 500 Is there another config to check? Thanks 2016-08-20 1:36 GMT+09:00 Bryan Call <[email protected]>: > I have seen issues with the write buffers filling and being flushed while it > stalls the process. This happened to me when doing large file transfers on > Linux. > > I ended up changing the value of vm.dirty_writeback_centisecs to 1500. > > $ sudo sysctl -a | grep writeback > vm.dirty_writeback_centisecs = 1500 > > Here is an article on the issue: > https://lonesysadmin.net/2013/12/22/better-linux-disk-caching-performance-vm-dirty_ratio/ > > -Bryan > > > > > On Aug 18, 2016, at 10:56 PM, Hiroaki Nakamura <[email protected]> wrote: > > Hi, > > I forgot to write traffic server version. > I'm using ATS 6.1.1 and using the raw partition for the cache storage. > > I also noticed vmstat disk/writ values remain 0 for one minute, > and then non-zero values follow and slow responses happen. > > > 2016-08-19 14:27 GMT+09:00 Hiroaki Nakamura <[email protected]>: > > Hi, > > I'm having a trouble that sometimes a request took 3 to 5 seconds on > approximately > every 39 minutes. > > I turned on the slow log and found out that cache_open_read_end is the most > time consuming. > > status: 200 unique id: redirection_tries: 0 bytes: 43 fd: 0 client > state: 0 server state: 9 ua_begin: 0.000 ua_first_read: 0.000 > ua_read_header_done: 0.000 cache_open_read_begin: 0.000 > cache_open_read_end: 2.536 dns_lookup_begin: 2.536 dns_lookup_end: > 2.536 server_connect: 2.537 server_first_read: 2.589 > server_read_header_done: 2.589 server_close: 2.589 ua_close: 2.589 > sm_finish: 2.589 plugin_active: 0.000 plugin_total: 0.000 > > Could you give me advice to know the reason why cache_open_read_end took so > long > and fix the slow responses? > > Thanks, > Hiroaki > >
