Project Description
zswap [1] is a linux kernel component that provides in-memory compression for swap pages. It already provides a limited form of deduplication: if a page is filled with the same value (e.g. all-zeroes) then only that value is kept instead of compressing the contents.
This project proposes to enhance zswap with a more general and powerful dedup capability: pages that contain the same content (as identified by a checksum or hash value across the entire page contents) will be stored only once in the compressed pool.
This would be somewhat similar in spirit to what ksm [2] does, that is consolidation of identical pages of anonymous memory. There are some differences though, primarily ksm requires userspace to explicitly opt-in (via madvise/MADV_MERGEABLE) and operates on active pages that have not been selected for eviction from memory. On the other hand zswap operates transparently from the applications (it applies to all pages of anonymous memory that are on their way to swap).
Goal for this Hackweek
Have a first working POC.
Resources
- [1] https://www.kernel.org/doc/html/latest/admin-guide/mm/zswap.html
- [2] https://www.kernel.org/doc/html/latest/admin-guide/mm/ksm.html
Looking for hackers with the skills:
This project is part of:
Hack Week 21
Activity
Comments
Be the first to comment!
Similar Projects
Create DRM drivers for VESA and EFI framebuffers by tdz
Description
We already have simpledrm for firmware framebuffers. But the driver is originally for ARM boards, not PCs. It is already overloaded with code to support both use cases. At the same time it is missing possible features for VESA and EFI, such as palette modes or EDID support. We should have DRM drivers for VESA and EFI interfaces. The infrastructure exists already and initial drivers can be forked from simpledrm.
Goals
- Initially, a bare driver for VESA or EFI should be created. It can take functionality from simpledrm.
- Then we can begin to add additional features. The boot loader can provide EDID data. With VGA hardware, VESA can support paletted modes or color management. Example code exists in vesafb.
Linux on Cavium CN23XX cards by tsbogend
Before Cavium switched to ARM64 CPUs they developed quite powerful MIPS based SOCs. The current upstream Linux kernel already supports some Octeon SOCs, but not the latest versions. Goal of this Hack Week project is to use the latest Cavium SDK to update the Linux kernel code to let it running on CN23XX network cards.
early stage kdump support by mbrugger
Project Description
When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.
Goal for the Hackweeks
- Investigate if this is possible and the implications it would have (done in HW21)
- Hack up a PoC (done in HW22 and HW23)
- Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).
update HW23
- I was able to include the crash kernel into the kernel Image.
- I'll need to find a way to load that from
init/main.c:start_kernel()
probably afterkcsan_init()
- I workaround for a smoke test was to hack
kexec_file_load()
systemcall which has two problems:- My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
- As the crash kernel is part of init.data it will be already stale once I can call
kexec_file_load()
from user-space.
The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.
update HW24
- Day1
- rebased on v6.12 with no problems others then me breaking the config
- setting up a new compilation and qemu/virtme env
- getting desperate as nothing works that used to work
- Day 2
- getting to call the invocation of loading the early kernel from
__init
afterkcsan_init()
- getting to call the invocation of loading the early kernel from
Day 3
- fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
- code refactoring
- I'm now able to load the crash kernel
- When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in
elfcorehdr_read_notes()
Day 4
- crash systems crashes (no pun intended) in
copy_old_mempage()
link; will need to understand elfcorehdr... - call path
vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()
- crash systems crashes (no pun intended) in
Day 5
- hacking
arch/arm64/kernel/crash_dump.c:copy_old_mempage()
to see if crash system really starts. It does. - fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/
- hacking
TODOs
- fix elfcorehdr so that we actually can make use of all this...
- test where in the boot
__init()
chain we can/should callkexec_early_dump()
Hacking on sched_ext by flonnegren
Description
Sched_ext upstream has some interesting issues open for grabs:
Goals
Send patches to sched_ext upstream
Also set up perfetto to trace some of the example schedulers.
Resources
https://github.com/sched-ext/scx
Improve various phones kernel mainline support (Qualcomm, Exynos, MediaTek) by pvorel
Similar to previous hackweeks ( https://hackweek.opensuse.org/projects/improve-qualcomm-soc-msm8994-slash-msm8992-kernel-mainline-support, https://hackweek.opensuse.org/projects/test-mainline-kernel-on-an-older-qualcomm-soc-msm89xx-explore-mainline-kernel-qualcomm-mainlining) try to improve kernel mainline support of various phones.
Result
In the end I concentrated again to msm8994:
- 507aae9a3549c ("arm64: dts: qcom: msm8994-angler: Enable power key, volume up/down") (will be in kernel 6.14)
- Testing of c910544d22347 ("arm64: dts: qcom: msm8994: Describe USB interrupts") (will be in kernel 6.14)
- WIP USB support for msm8994