| Message ID | 20220221195410.9172-5-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | fbdev: Improve performance of fbdev console | expand |
On Mon, 21 Feb 2022 20:54:09 +0100 Thomas Zimmermann <tzimmermann@suse.de> wrote: > Improve the performance of sys_imageblit() by manually unrolling sys? > the inner blitting loop and moving some invariants out. The compiler > failed to do this automatically. This change keeps cfb_imageblit() > in sync with sys_imagebit(). This is correct here. > > A microbenchmark measures the average number of CPU cycles > for sys_imageblit() after a stabilizing period of a few minutes sys? > (i7-4790, FullHD, simpledrm, kernel with debugging). > > sys_imageblit(), new: 15724 cycles sys? > cfb_imageblit(): old: 30566 cycles > > In the optimized case, cfb_imageblit() is now ~2x faster than before. > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > --- > drivers/video/fbdev/core/cfbimgblt.c | 51 +++++++++++++++++++++++----- > 1 file changed, 42 insertions(+), 9 deletions(-) Just noticed some confusion in the commit message. Thanks, pq
Hi Am 22.02.22 um 14:01 schrieb Pekka Paalanen: > On Mon, 21 Feb 2022 20:54:09 +0100 > Thomas Zimmermann <tzimmermann@suse.de> wrote: > >> Improve the performance of sys_imageblit() by manually unrolling > > sys? > >> the inner blitting loop and moving some invariants out. The compiler >> failed to do this automatically. This change keeps cfb_imageblit() >> in sync with sys_imagebit(). > > This is correct here. > >> >> A microbenchmark measures the average number of CPU cycles >> for sys_imageblit() after a stabilizing period of a few minutes > > sys? > >> (i7-4790, FullHD, simpledrm, kernel with debugging). >> >> sys_imageblit(), new: 15724 cycles > > sys? > >> cfb_imageblit(): old: 30566 cycles >> >> In the optimized case, cfb_imageblit() is now ~2x faster than before. >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> --- >> drivers/video/fbdev/core/cfbimgblt.c | 51 +++++++++++++++++++++++----- >> 1 file changed, 42 insertions(+), 9 deletions(-) > > Just noticed some confusion in the commit message. I copied some of the text from the other commit and I could have sworn I updated it. But apparently not. Best regards Thomas > > > Thanks, > pq
diff --git a/drivers/video/fbdev/core/cfbimgblt.c b/drivers/video/fbdev/core/cfbimgblt.c index 01b01a279681..7361cfabdd85 100644 --- a/drivers/video/fbdev/core/cfbimgblt.c +++ b/drivers/video/fbdev/core/cfbimgblt.c @@ -218,23 +218,29 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info * { u32 fgx = fgcolor, bgx = bgcolor, bpp = p->var.bits_per_pixel; u32 ppw = 32/bpp, spitch = (image->width + 7)/8; - u32 bit_mask, end_mask, eorx, shift; + u32 bit_mask, eorx; const char *s = image->data, *src; u32 __iomem *dst; const u32 *tab = NULL; + size_t tablen; + u32 colortab[16]; int i, j, k; switch (bpp) { case 8: tab = fb_be_math(p) ? cfb_tab8_be : cfb_tab8_le; + tablen = 16; break; case 16: tab = fb_be_math(p) ? cfb_tab16_be : cfb_tab16_le; + tablen = 4; break; case 32: - default: tab = cfb_tab32; + tablen = 2; break; + default: + return; } for (i = ppw-1; i--; ) { @@ -248,15 +254,42 @@ static inline void fast_imageblit(const struct fb_image *image, struct fb_info * eorx = fgx ^ bgx; k = image->width/ppw; - for (i = image->height; i--; ) { - dst = (u32 __iomem *) dst1, shift = 8; src = s; + for (i = 0; i < tablen; ++i) + colortab[i] = (tab[i] & eorx) ^ bgx; - for (j = k; j--; ) { - shift -= ppw; - end_mask = tab[(*src >> shift) & bit_mask]; - FB_WRITEL((end_mask & eorx)^bgx, dst++); - if (!shift) { shift = 8; src++; } + for (i = image->height; i--; ) { + dst = (u32 __iomem *)dst1; + src = s; + + switch (ppw) { + case 4: /* 8 bpp */ + for (j = k; j; j -= 2, ++src) { + FB_WRITEL(colortab[(*src >> 4) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 0) & bit_mask], dst++); + } + break; + case 2: /* 16 bpp */ + for (j = k; j; j -= 4, ++src) { + FB_WRITEL(colortab[(*src >> 6) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 4) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 2) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 0) & bit_mask], dst++); + } + break; + case 1: /* 32 bpp */ + for (j = k; j; j -= 8, ++src) { + FB_WRITEL(colortab[(*src >> 7) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 6) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 5) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 4) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 3) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 2) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 1) & bit_mask], dst++); + FB_WRITEL(colortab[(*src >> 0) & bit_mask], dst++); + } + break; } + dst1 += p->fix.line_length; s += spitch; }
Improve the performance of sys_imageblit() by manually unrolling the inner blitting loop and moving some invariants out. The compiler failed to do this automatically. This change keeps cfb_imageblit() in sync with sys_imagebit(). A microbenchmark measures the average number of CPU cycles for sys_imageblit() after a stabilizing period of a few minutes (i7-4790, FullHD, simpledrm, kernel with debugging). sys_imageblit(), new: 15724 cycles cfb_imageblit(): old: 30566 cycles In the optimized case, cfb_imageblit() is now ~2x faster than before. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> --- drivers/video/fbdev/core/cfbimgblt.c | 51 +++++++++++++++++++++++----- 1 file changed, 42 insertions(+), 9 deletions(-)