From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- drivers/video/fbdev/tdfxfb.c | 1827 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1827 insertions(+) create mode 100644 drivers/video/fbdev/tdfxfb.c (limited to 'drivers/video/fbdev/tdfxfb.c') diff --git a/drivers/video/fbdev/tdfxfb.c b/drivers/video/fbdev/tdfxfb.c new file mode 100644 index 000000000..281987502 --- /dev/null +++ b/drivers/video/fbdev/tdfxfb.c @@ -0,0 +1,1827 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * tdfxfb.c + * + * Author: Hannu Mallat + * + * Copyright © 1999 Hannu Mallat + * All rights reserved + * + * Created : Thu Sep 23 18:17:43 1999, hmallat + * Last modified: Tue Nov 2 21:19:47 1999, hmallat + * + * I2C part copied from the i2c-voodoo3.c driver by: + * Frodo Looijaard , + * Philip Edelbrock , + * Ralph Metzler , and + * Mark D. Studebaker + * + * Lots of the information here comes from the Daryll Strauss' Banshee + * patches to the XF86 server, and the rest comes from the 3dfx + * Banshee specification. I'm very much indebted to Daryll for his + * work on the X server. + * + * Voodoo3 support was contributed Harold Oga. Lots of additions + * (proper acceleration, 24 bpp, hardware cursor) and bug fixes by Attila + * Kesmarki. Thanks guys! + * + * Voodoo1 and Voodoo2 support aren't relevant to this driver as they + * behave very differently from the Voodoo3/4/5. For anyone wanting to + * use frame buffer on the Voodoo1/2, see the sstfb driver (which is + * located at http://www.sourceforge.net/projects/sstfb). + * + * While I _am_ grateful to 3Dfx for releasing the specs for Banshee, + * I do wish the next version is a bit more complete. Without the XF86 + * patches I couldn't have gotten even this far... for instance, the + * extensions to the VGA register set go completely unmentioned in the + * spec! Also, lots of references are made to the 'SST core', but no + * spec is publicly available, AFAIK. + * + * The structure of this driver comes pretty much from the Permedia + * driver by Ilario Nardinocchi, which in turn is based on skeletonfb. + * + * TODO: + * - multihead support (basically need to support an array of fb_infos) + * - support other architectures (PPC, Alpha); does the fact that the VGA + * core can be accessed only thru I/O (not memory mapped) complicate + * things? + * + * Version history: + * + * 0.1.4 (released 2002-05-28) ported over to new fbdev api by James Simmons + * + * 0.1.3 (released 1999-11-02) added Attila's panning support, code + * reorg, hwcursor address page size alignment + * (for mmapping both frame buffer and regs), + * and my changes to get rid of hardcoded + * VGA i/o register locations (uses PCI + * configuration info now) + * 0.1.2 (released 1999-10-19) added Attila Kesmarki's bug fixes and + * improvements + * 0.1.1 (released 1999-10-07) added Voodoo3 support by Harold Oga. + * 0.1.0 (released 1999-10-06) initial version + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include