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Kernel: Start implementing purgeable memory support

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It's now possible to get purgeable memory by using mmap(MAP_PURGEABLE).
Purgeable memory has a "volatile" flag that can be set using madvise():

- madvise(..., MADV_SET_VOLATILE)
- madvise(..., MADV_SET_NONVOLATILE)

When in the "volatile" state, the kernel may take away the underlying
physical memory pages at any time, without notifying the owner.
This gives you a guilt discount when caching very large things. :^)

Setting a purgeable region to non-volatile will return whether or not
the memory has been taken away by the kernel while being volatile.
Basically, if madvise(..., MADV_SET_NONVOLATILE) returns 1, that means
the memory was purged while volatile, and whatever was in that piece
of memory needs to be reconstructed before use.
This commit is contained in:
Andreas Kling 2019-12-09 19:12:38 +01:00
parent 7248c34e35
commit dbb644f20c
13 changed files with 196 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

8
Kernel/FileSystem/ProcFS.cpp
View file

@ -24,6 +24,7 @@
#include <Kernel/Net/UDPSocket.h>
#include <Kernel/PCI.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/PurgeableVMObject.h>
#include <LibC/errno_numbers.h>
enum ProcParentDirectory {
@ -262,6 +263,11 @@ Optional<KBuffer> procfs$pid_vm(InodeIdentifier identifier)
region_object.add("writable", region.is_writable());
region_object.add("stack", region.is_stack());
region_object.add("shared", region.is_shared());
region_object.add("purgeable", region.vmobject().is_purgeable());
if (region.vmobject().is_purgeable()) {
region_object.add("volatile", static_cast<const PurgeableVMObject&>(region.vmobject()).is_volatile());
}
region_object.add("purgeable", region.vmobject().is_purgeable());
region_object.add("address", region.vaddr().get());
region_object.add("size", (u32)region.size());
region_object.add("amount_resident", (u32)region.amount_resident());
@ -716,6 +722,8 @@ Optional<KBuffer> procfs$all(InodeIdentifier)
process_object.add("amount_virtual", (u32)process.amount_virtual());
process_object.add("amount_resident", (u32)process.amount_resident());
process_object.add("amount_shared", (u32)process.amount_shared());
process_object.add("amount_purgeable_volatile", (u32)process.amount_purgeable_volatile());
process_object.add("amount_purgeable_nonvolatile", (u32)process.amount_purgeable_nonvolatile());
process_object.add("icon_id", process.icon_id());
auto thread_array = process_object.add_array("threads");
process.for_each_thread([&](const Thread& thread) {