x86-64 has five symbols within VDSO that we need to emulate.
Pass this through either glibc or host vdso if the symbol exists.
AArch64 doesn't have the time or getcpu vdso interface, so fall down
glibc instead.
Kind of sucky that SVE doesn't have a convenient way to manipulate
predicate registers with immediates or anything to make this nicer (that
I know of).
Having to use a temp to clear the upper part of the vector reliably is
bleh.
Due to how the 64-bit allocator previously worked, it was never subjected to memory
regions larger than 64GB to be tracked. With the change in
PR #1885, this has changed to have regions that will hit sizes larger
than 170TB on some platforms.
Better yet, even with smaller regions it still had a performance issue,
it just wasn't as visible.
First problem: We used MemSet instead of MemClear for the live page
clearing. This caused pages to be claimed as "always in use".
This would cause us to always scan the entire region on allocation, find
that it didn't work and allocate a fresh region on every slab
allocation.
jemalloc saving us here since it allocates slabs from the OS fairly
aggressively.
Second problem: We used MemSet (now changed to MemClear) to "clear" the
state tracking for pages.
This causes ~600MB of memory to be used purely for state tracking.
This was physically backed since we were writing to every bit of
tracking for handling 256TB of VA.
This had a fault dance with the kernel for every new page being hit
here.
Instead of clearing the the bits with a memset, clear it with madvise so
it doesn't consume physical pages at all.
This means we use significantly less physical memory for 32-bit
applications.
With this change, pressure-vessel startup time goes from 24 seconds down
to 17 seconds. 70% of the original startup time.
But really the main savings here comes from the memory reduction that
PR #1885 ballooned, but has been an unseen problem before.
Before that PR we were burning 2MB of physical memory per region for no
reason.
After that PR we were burning up to 600MB of physical memory per region
for no reason. Changing a bit depending on how large the region ended up
being.
This now ends up being 2 pages starting out and grows as more pages are
are used. A significant improvement.
We have separate configurations for the Application path versus the
application name we are using as a configuration choice.
Example 1: FEXBash "wine Crysis64.exe"
Previous APP_FILENAME will contain `/usr/bin/wine`, which is still used
elsewhere.
This new APP_CONFIG_NAME will contain `Crysis64.exe`
Example 2: FEXBash glxgears
Previous APP_FILENAME will contain `/usr/bin/glxgears`
APP_CONFIG_NAME will contain `glxgears`
We didn't have this exposed any other way before.
This is necessary for the fexserver to function correctly when chrooting
in to our rootfs and doing things.
Requires independent rootfs script modifications which will come with
the next rootfs update.
Problem comes down to a chroot supporting multiple users, where our
typical use case is only one user. Bind the server file to a single
server for the entire chroot session regardless of users, solving this
problem inside the chroot.
Fixes apt-get inside of chroot, which runs as user _apt.
This changes how host trampolines for guest functions are created. Instead
of doing this purely on the guest-side, it's either the host-side that
creates them in a single step *or* a cooperative two-step initialization
process must be used. In the latter, trampolines are allocated and partially
initialized on the guest and must be finalized on the host before use.
lioncash