Begin forwarded message: Date: Mon, 15 Nov 2010 11:52:05 +0800 From: r6144 <rainy6144@xxxxxxxxx> To: linux-kernel@xxxxxxxxxxxxxxx Subject: Sluggishness on a GEM system due to SELinux's sidtab_search_context() as well as get_unmapped_area() Hello, I'm noticing significant sluggishness when switching into a workspace where Evolution is running. My kernel is Fedora 12's 2.6.32.16-150.fc12.x86_64 (I know it is old...), and the open source radeon (r600) driver is used. Oprofile shows the follows: CPU: Core 2, speed 2003 MHz (estimated) Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000 Counted INST_RETIRED_ANY_P events (number of instructions retired) with a unit mask of 0x00 (No unit mask) count 100000 samples % samples % image name app name symbol name 126807 31.2201 38744 28.3866 vmlinux Xorg (deleted) find_vma 48661 11.9804 3474 2.5453 vmlinux Xorg (deleted) mls_compute_sid 41806 10.2927 5700 4.1762 vmlinux Xorg (deleted) sidtab_search_context 11888 2.9268 4234 3.1021 Xorg (deleted) Xorg (deleted) /usr/bin/Xorg (deleted) 8660 2.1321 1589 1.1642 drm Xorg (deleted) /drm 6228 1.5333 6773 4.9624 radeon Xorg (deleted) /radeon 6214 1.5299 1832 1.3423 libc-2.11.2.so (deleted) Xorg (deleted) /lib64/libc-2.11.2.so (deleted) 5542 1.3644 4929 3.6113 libpixman-1.so.0.16.6.#prelink#.3I5wow (deleted) Xorg (deleted) /usr/lib64/libpixman-1.so.0.16.6.#prelink#.3I5wow (deleted) 4149 1.0215 1776 1.3012 libexa.so Xorg (deleted) /usr/lib64/xorg/modules/libexa.so 4140 1.0193 640 0.4689 vmlinux oprofiled mls_compute_sid 3183 0.7837 847 0.6206 vmlinux Xorg (deleted) arch_get_unmapped_area_topdown ... Although I haven't looked into it, presumably Evolution is asking the X server to create and map a lot of TTM objects (pixmaps?). The creation of each object uses shmem_file_setup() and thus necessitates SELinux calls, and since the X process already has a lot of mappings (one mapping for each XRender glyph it seems, with "wc -l /proc/`pgrep Xorg`/maps" returning 6766), the mapping part could also be slow. I think the slowness of find_vma is related to https://bugzilla.kernel.org/show_bug.cgi?id=17531 . mls_compute_sid() did a linear search over the range transition rules and was therefore slow, but more recent kernels use a hash table so this problem has been solved. Another offender is sidtab_search_context() used to convert a SELinux context back into an sid, which is also a linear search as there is only a sid => context hash table, and I haven't seen any recent changes in this area. Please CC me as I'm not subscribed. r6144 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@xxxxxxxxxxxxx with the words "unsubscribe selinux" without quotes as the message.
