diff options
Diffstat (limited to 'hurd/translator')
| -rw-r--r-- | hurd/translator/hello.mdwn | 14 | ||||
| -rw-r--r-- | hurd/translator/tmpfs/tmpfs_vs_defpager.mdwn | 37 |
2 files changed, 51 insertions, 0 deletions
diff --git a/hurd/translator/hello.mdwn b/hurd/translator/hello.mdwn new file mode 100644 index 00000000..bd56cd76 --- /dev/null +++ b/hurd/translator/hello.mdwn @@ -0,0 +1,14 @@ +[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +The *hello* translator is an example of a simple [[libtrivfs]]-based one-node +[[translator]]. It is shipped as part of the [[Hurd source code +repository|source_repositories]], and exists in a single-threaded and a +multi-threaded variant. diff --git a/hurd/translator/tmpfs/tmpfs_vs_defpager.mdwn b/hurd/translator/tmpfs/tmpfs_vs_defpager.mdwn index a9317c21..5228515f 100644 --- a/hurd/translator/tmpfs/tmpfs_vs_defpager.mdwn +++ b/hurd/translator/tmpfs/tmpfs_vs_defpager.mdwn @@ -233,3 +233,40 @@ See also: [[open_issues/resource_management_problems/pagers]]. I have never looked at it. [[open_issues/mach-defpager_vs_defpager]]. + + +# IRC, freenode, #hurd, 2011-11-08 + + <mcsim> who else uses defpager besides tmpfs and kernel? + <braunr> normally, nothing directly + <mcsim> than why tmpfs should use defpager? + <braunr> it's its backend + <braunr> backign store rather + <braunr> the backing store of most file systems are partitions + <braunr> tmpfs has none, it uses the swap space + <mcsim> if we allocate memory for tmpfs using vm_allocate, will it be able + to use swap partition? + <braunr> it should + <braunr> vm_allocate just maps anonymous memory + <braunr> anonymous memory uses swap space as its backing store too + <braunr> but be aware that this part of the vm system is known to have + deficiencies + <braunr> which is why all mach based implementations have rewritten their + default pager + <mcsim> what kind of deficiencies? + <braunr> bugs + <braunr> and design issues, making anonymous memory fragmentation horrible + <antrik> mcsim: vm_allocate doesn't return a memory object; so it can't be + passed to clients for mmap() + <mcsim> antrik: I use vm_allocate in pager_read_page + <antrik> mcsim: well, that means that you have to actually implement a + pager yourself + <antrik> also, when the kernel asks the pager to write back some pages, it + expects the memory to become free. if you are "paging" to ordinary + anonymous memory, this doesn't happen; so I expect it to have a very bad + effect on system performance + <antrik> both can be avoided by just passing a real anonymous memory + object, i.e. one provided by the defpager + <antrik> only problem is that the current defpager implementation can't + really handle that... + <antrik> at least that's my understanding of the situation |