-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 12/01/2020 17.35, Anton Aylward wrote: | On 12/01/2020 05:47, Carlos E. R. wrote: |> On 12/01/2020 09.57, jdd@dodin.org wrote: |>> Le 11/01/2020 à 22:38, Carlos E. R. a écrit : | |> The processor can not use something that is in swap this moment; |> it has to copy it first to RAM. |> |> So in a memory almost full situation the kernel first finds some |> block of memory that is not needed now (maybe by counting how |> long it has been since last used), writes it to swap, frees that |> block, then read from swap the block that it needs and writes it |> to the free ram. | | It may not need to be written to swap. If this was a code page or | a page from some other, similarly memory mapped file, the there is | no need to write it to swap. If it is needed again it can be | retrieved from the file system. | | Swap is only used for a program's volatile data. "only". That "only" is typically 5 GiB in my system after both FF and Th have been running a day or two, with a few more apps. Is there somewhere a measure the amount of memory mapped files that are not in RAM this second? |> So the operation is slow. The situation is called trashing; with |> a | ^^^^^^^^ tHrashing Blame Th speller. :-p |> rotating disk you hear it working and the system becomes slow. | | |> Approximately. There may be details I do not consider but Andrei |> does :-) |> |> Ideally, if I'm working with Thunderbird, and then go to the |> workspace where LibreOffice is open, Thunderbird would be sent |> to swap, and LO would be taken out of swap. But I doubt the |> kernel knows my intentions of using LO for a while and not Th. | | Actually it makes some accurate prognostications. For a start, | both make use of the same shared libraries. Not just libc but the | GTK stuff as well. Both are heavy on startup, but the startup | files and the startup code can then be discarded. | | Neither Thunderbird nor LO are 'sent to swap', only their volatile | data. I said approximately ;-) | A lot of the difference between you TB volatile data and my TB | volatile data lies in the details of configuration. Plugins | contribute heavily! | |> Now, 5 gigs of ram + 5 gigs of swap approximates 10 gigs of |> memory. That imprecise saying is good enough for me :-) |> |> This instant, my 8 GiB system is using 7.2 GiB of swap, but |> there are 3.1 GiB of ram available (between fully free (2.66) |> and buffers/cache (1.1)). But it is fresh out of hibernation, |> the proportion of swap is higher. | | Unlike older models, that 'buffer/cache' is just an expression of | where some of the dynamics of virtual memory is at at the moment. | | - a disk-less workstation that runs entirely off networking will | have a very different view of the buffer/cache! | | - a CPU compute intensive application (think: mining bitcoins?) is | going to have a very different profile | | - a 'headless' server, one not running X or the associated | interactive applications (TB, FF, LO DT) and graphics will use | network IO buffer heavily. A simplistic memory report (perhaps to | a ssh login) is going to give inadequate information about what | buffers are being used. | | For some of the above ... why would you cache a buffer? | - -- Cheers / Saludos, Carlos E. R. (from 15.1 x86_64 at Telcontar) -----BEGIN PGP SIGNATURE----- iF0EARECAB0WIQQZEb51mJKK1KpcU/W1MxgcbY1H1QUCXhtR1QAKCRC1MxgcbY1H 1QAYAJ9ML3COUWsJEjrz0BVdbSnnO2bkLwCeJ7LDXlQpAjUP/uVmvQOhdzjJjNk= =8jLN -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org