Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

User mode uses inefficient structures to store information on pages #240

Open
kwitaszczyk opened this issue Oct 16, 2023 · 0 comments
Open

User mode uses inefficient structures to store information on pages #240

kwitaszczyk opened this issue Oct 16, 2023 · 0 comments
Labels
user-mode

Comments

@kwitaszczyk
Copy link
Member

kwitaszczyk commented Oct 16, 2023 •
edited
Loading

Our current QEMU version uses inefficient structures to store PageDesc objects used in TCG. This issue was fixed in upstream [1] [2] [3] by using interval trees. Without these improvements merged into our user mode, we cannot use CheriBSD with snmalloc as the default allocator under the user mode because it creates a huge mapping (for a region of 512 GB in my case) with mmap(2) that itself takes several seconds.

[1] https://gitlab.com/qemu-project/qemu/-/issues/290
[2] https://gitlab.com/qemu-project/qemu/-/issues/967
[3] https://gitlab.com/qemu-project/qemu/-/issues/1214
[4] https://github.com/CTSRD-CHERI/cheribsd/blob/bcabfe1f46bd993c762a1816b6fb88cd8a9fbfc3/contrib/subrepo-snmalloc/src/snmalloc/pal/pal_posix.h#L332
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
user-mode
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
1 participant
@kwitaszczyk