On Tue, Nov 14, 2017 at 6:12 PM, Alex Rousskov <rousskov@xxxxxxxxxxxxxxxxxxxxxxx> wrote: > On 11/14/2017 08:41 AM, Bike dernikov1 wrote: >> On Mon, Nov 13, 2017 at 4:36 PM, Alex Rousskov wrote: >>> On 11/13/2017 02:34 AM, Bike dernikov1 wrote: >>>> Swap could be used to translate back data to mem if used, but it >>>> stays on disk and purge after some time if not used ? > >>> The purging bit is wrong. Think of swap as very very very slow RAM. > >> So, when squid need something from swap, it will load that data back to ram. > > In this context, swap is an OS-level concept. Squid does not know that > the OS memory manager has swapped some of Squid data from RAM to disk. > OS does not know what swapped out data means to Squid. When Squid tries > to access data at a swapped out address, the OS blocks the Squid process > and loads the missing data from disk into RAM (usually after swapping > out some RAM bytes to free RAM space for those requested bytes). > > Here, "data" essentially means any sequence of bytes allocated by Squid. > For example, some of those swapped out bytes may have nothing to do with > Squid memory cache. Swapped out bytes can even be Squid binary code. > > >> For purge, data then stay in swap forever ? > > Swapped out process data stays swapped out until it is either accessed > by the process (and is swapped in by the OS) or the process terminates > (without accessing those swapped out bytes). The latter is unlikely for > Squid data unless the Squid process dies prematurely (i.e., without > doing internal cleanup). > > HTH, > > Alex. Superb explanation. I think that now I understand process much better. If i can ask under same title: Yesterday we had error in logs: syslog, cache.log, dmesg,access.log segfault at 8 ip ....... sp ..... error 4 is squid process pid exited due to signal 11 with status 0 Squid restarted, that was at the end of work, and i didn't notice change while surfing. I noticed change in used memory, after i went trough logs, and found segfault. Can you point me, how to analyze what happened. Can that be problem with kernel ? Thanks for help. _______________________________________________ squid-users mailing list squid-users@xxxxxxxxxxxxxxxxxxxxx http://lists.squid-cache.org/listinfo/squid-users
