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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 9A18821BE4 X-Spam-Level: X-Spamd-Result: default: False [-6.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; DWL_DNSWL_MED(-2.00)[suse.de:dkim]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; FREEMAIL_TO(0.00)[intel.com,redhat.com,linux.intel.com,kernel.org,gmail.com,ffwll.ch,lists.linux.dev,lists.freedesktop.org,vger.kernel.org]; RCPT_COUNT_TWELVE(0.00)[14]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCVD_TLS_ALL(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -6.51 X-Spam-Flag: NO Hi Am 09.09.24 um 07:15 schrieb Yan Zhao: > Use ioremap_wc() instead of ioremap() to map framebuffer during driver > probing phase. > > Using ioremap() results in a VA being mapped with PAT=UC-. Additionally, > on x86 architectures, ioremap() invokes memtype_reserve() to reserve the > memory type as UC- for the physical range. This reservation can cause > subsequent calls to ioremap_wc() to fail to map the VA with PAT=WC to the > same physical range for framebuffre in ttm_kmap_iter_linear_io_init(). > Consequently, the operation drm_gem_vram_bo_driver_move() -> > ttm_bo_move_memcpy() -> ttm_move_memcpy() becomes significantly slow on > platforms where UC memory access is slow. I've noticed this too and pushed a major update that replaces the entire memory management. [1] The patch is still welcome, I think, but you may want to rebase onto the latest drm-misc-next branch. [2] Best regards Thomas [1] https://patchwork.freedesktop.org/series/138086/ [2] https://gitlab.freedesktop.org/drm/misc/kernel/-/tree/drm-misc-next > > Here's the performance data measured in a guest on the physical machine > "Sapphire Rapids XCC". > With host KVM honors guest PAT memory types, the effective memory type > for this framebuffer range is > - WC when ioremap_wc() is used in driver probing phase > - UC- when ioremap() is used. > > The data presented is an average from 10 execution runs. > The memcpy range for the data is > mem->bus.offset=0xfd000000, mem->size=0x3e8000. > > -------------------------------------------------------------- > | in bochs_hw_init() | > | ioremap() | ioremap_wc() | > ------------------------------|----------------|--------------| > cycles of | 2227.4M | 17.8M | > drm_gem_vram_bo_driver_move() | | | > ------------------------------|----------------|--------------| > time of | 1.24s | 0.01s | > drm_gem_vram_bo_driver_move() | | | > -------------------------------------------------------------- > > Reported-by: Vitaly Kuznetsov > Closes: https://lore.kernel.org/all/87jzfutmfc.fsf@redhat.com/#t > Cc: Sean Christopherson > Cc: Paolo Bonzini > Cc: Kevin Tian > Signed-off-by: Yan Zhao > --- > drivers/gpu/drm/tiny/bochs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c > index 31fc5d839e10..6414f0a72f6a 100644 > --- a/drivers/gpu/drm/tiny/bochs.c > +++ b/drivers/gpu/drm/tiny/bochs.c > @@ -261,7 +261,7 @@ static int bochs_hw_init(struct drm_device *dev) > if (pci_request_region(pdev, 0, "bochs-drm") != 0) > DRM_WARN("Cannot request framebuffer, boot fb still active?\n"); > > - bochs->fb_map = ioremap(addr, size); > + bochs->fb_map = ioremap_wc(addr, size); > if (bochs->fb_map == NULL) { > DRM_ERROR("Cannot map framebuffer\n"); > return -ENOMEM; -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)