Re: [CentOS] Disk read io very high, but no process perform io read
I haven't been following this thread closely, so may be off target. When pages are moved out of the working set they are either "clean" or "dirty". Clean pages have not been modified since they were originally moved into memory whereas dirty pages have been changed. A dirty page can become clean if it is written back to disk. Typically (though not always) this is a write to swap. Read only pages, such as code or data will always be clean, so can be dropped when required. When a hard fault occurs then pages have to be read from disk, somewhere. That somewhere could be swap, but can also be program images or files. It may be that what you observe is this latter process. HTH, Martin On 12/03/2021 01:29, yf chu wrote: yes. I suspect it has something to do with swapping. but swap is turned off on this server. here is the result of free -m. totalusedfree shared buff/cache available Mem: 128174 97449 2440041586325 25232 Swap: 0 0 0 We have other servers. The processes running on these servers are same. but on other servers, the size of buff/cache is larger than the size on the server which experienced the problem and the size of "free" is smaller than the size on the server which experienced the problem. -- J Martin Rushton MBCS ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Disk read io very high, but no process perform io read
yes. I suspect it has something to do with swapping. but swap is turned off on this server. here is the result of free -m. totalusedfree shared buff/cache available Mem: 128174 97449 2440041586325 25232 Swap: 0 0 0 We have other servers. The processes running on these servers are same. but on other servers, the size of buff/cache is larger than the size on the server which experienced the problem and the size of "free" is smaller than the size on the server which experienced the problem. 在 2021-03-10 14:30:00，"Thomas Stephen Lee" 写道： >On Sat, Mar 6, 2021 at 6:37 AM yf chu wrote: >> >> no, not vm >> >> >> >> >> | | >> yf chu >> | >> | >> 邮箱：cyf...@163.com >> | >> >> 签名由 网易邮箱大师 定制 >> >> On 03/05/2021 23:37, Matthew Miller wrote: >> On Fri, Mar 05, 2021 at 03:54:14PM +0800, yf chu wrote: >> > We have experienced a very weird problem. The load of the server machine >> > is very high. We use "pidstat" and find that the disk read io is very high. >> >> Is this system a VM? >> >> -- >> Matthew Miller >> >> Fedora Project Leader > >Hi, > >Is this due to swapping? > >what is the output of > >free -m > >--- >Lee >___ >CentOS mailing list >CentOS@centos.org >https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Disk read io very high, but no process perform io read
yes. I suspect it has something to do with swapping. but swap is turned off on this server. here is the result of free -m. totalusedfree shared buff/cache available Mem: 128174 97449 2440041586325 25232 Swap: 0 0 0 We have other servers. The processes running on these servers are same. but on other servers, the size of buff/cache is larger than the size on the server which experienced the problem and the size of "free" is smaller than the size on the server which experienced the problem. 在 2021-03-10 14:30:00，"Thomas Stephen Lee" 写道： >On Sat, Mar 6, 2021 at 6:37 AM yf chu wrote: >> >> no, not vm >> >> >> >> >> | | >> yf chu >> | >> | >> 邮箱：cyf...@163.com >> | >> >> 签名由 网易邮箱大师 定制 >> >> On 03/05/2021 23:37, Matthew Miller wrote: >> On Fri, Mar 05, 2021 at 03:54:14PM +0800, yf chu wrote: >> > We have experienced a very weird problem. The load of the server machine >> > is very high. We use "pidstat" and find that the disk read io is very high. >> >> Is this system a VM? >> >> -- >> Matthew Miller >> >> Fedora Project Leader > >Hi, > >Is this due to swapping? > >what is the output of > >free -m > >--- >Lee >___ >CentOS mailing list >CentOS@centos.org >https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
