From 399df7aef871f7db8ab3adbe3eee6b0f5af99989 Mon Sep 17 00:00:00 2001 From: Richard Grenville Date: Fri, 26 Oct 2012 11:12:28 +0800 Subject: [PATCH] Bug fix #7: Correct a possible issue in VSync - I realized I might have fundamentally misunderstood VSync. This commit tries to fix the possible problem, or at least move the tearing line close to the top of the screen. - Software VSync is replaced by --sw-opti (software optimization), as I guess it isn't possible at all to do VSync without driver support. - Add "vsync" and "sw-opti" as configuration file options. --- compton.c | 214 +++++++++++++++++++++++++++--------------------------- compton.h | 32 ++++++-- 2 files changed, 133 insertions(+), 113 deletions(-) diff --git a/compton.c b/compton.c index 833efeaa9..4394e8088 100755 --- a/compton.c +++ b/compton.c @@ -74,12 +74,11 @@ Bool reg_ignore_expire = False; /// Window ID of the window we register as a symbol. Window reg_win = 0; -/// Currently used refresh rate. Used for Software VSync. +/// Currently used refresh rate. Used for sw_opti. short refresh_rate = 0; -/// Interval between refresh in nanoseconds. Used for Software VSync. +/// Interval between refresh in nanoseconds. Used for sw_opti. unsigned long refresh_intv = 0; -/// Nanosecond-level offset of the first painting. -/// Used for Software VSync. +/// Nanosecond-level offset of the first painting. Used for sw_opti. long paint_tm_offset = 0; #ifdef CONFIG_VSYNC_DRM @@ -179,6 +178,7 @@ static options_t opts = { .paint_on_overlay = False, .refresh_rate = 0, + .sw_opti = False, .vsync = VSYNC_NONE, .dbe = False, @@ -1568,6 +1568,10 @@ win_paint_win(Display *dpy, win *w, Picture tgt_buffer) { static void paint_all(Display *dpy, XserverRegion region, win *t) { +#ifdef DEBUG_REPAINT + static struct timespec last_paint = { 0 }; +#endif + win *w; XserverRegion reg_paint = None, reg_tmp = None, reg_tmp2 = None; @@ -1616,7 +1620,6 @@ paint_all(Display *dpy, XserverRegion region, win *t) { #endif #ifdef DEBUG_REPAINT - print_timestamp(); printf("paint:"); #endif @@ -1700,7 +1703,6 @@ paint_all(Display *dpy, XserverRegion region, win *t) { #ifdef DEBUG_REPAINT printf("\n"); - fflush(stdout); #endif // Free up all temporary regions @@ -1708,6 +1710,9 @@ paint_all(Display *dpy, XserverRegion region, win *t) { XFixesDestroyRegion(dpy, reg_tmp); XFixesDestroyRegion(dpy, reg_tmp2); + // Wait for VBlank + vsync_wait(); + // DBE painting mode, only need to swap the buffer if (opts.dbe) { XdbeSwapInfo swap_info = { @@ -1725,6 +1730,20 @@ paint_all(Display *dpy, XserverRegion region, win *t) { tgt_picture, 0, 0, 0, 0, 0, 0, root_width, root_height); } + + XFlush(dpy); + +#ifdef DEBUG_REPAINT + // It prints the timestamp in the wrong line, but... + print_timestamp(); + struct timespec now = get_time_timespec(); + struct timespec diff = { 0 }; + timespec_subtract(&diff, &now, &last_paint); + printf("[ %5ld:%09ld ] ", diff.tv_sec, diff.tv_nsec); + last_paint = now; + fflush(stdout); +#endif + } static void @@ -3304,10 +3323,8 @@ usage(void) { " Specify refresh rate of the screen. If not specified or 0, compton\n" " will try detecting this with X RandR extension.\n" "--vsync vsync-method\n" - " Set VSync method. There are 4 VSync methods currently available:\n" + " Set VSync method. There are 2 VSync methods currently available:\n" " none = No VSync\n" - " sw = software VSync, basically limits compton to send a request\n" - " every 1 / refresh_rate second. Experimental.\n" " drm = VSync with DRM_IOCTL_WAIT_VBLANK. May only work on some\n" " drivers. Experimental.\n" " opengl = Try to VSync with SGI_swap_control OpenGL extension. Only\n" @@ -3321,6 +3338,9 @@ usage(void) { " (hopefully) eliminate tearing.\n" "--paint-on-overlay\n" " Painting on X Composite overlay window.\n" + "--sw-opti\n" + " Limit compton to repaint at most once every 1 / refresh_rate\n" + " second to boost performance. Experimental.\n" "\n" "Format of a condition:\n" "\n" @@ -3533,6 +3553,29 @@ open_config_file(char *cpath, char **ppath) { return NULL; } +/** + * Parse a VSync option argument. + */ +static inline void +parse_vsync(const char *optarg) { + const static char * const vsync_str[] = { + "none", // VSYNC_NONE + "drm", // VSYNC_DRM + "opengl", // VSYNC_OPENGL + }; + + vsync_t i; + + for (i = 0; i < (sizeof(vsync_str) / sizeof(vsync_str[0])); ++i) + if (!strcasecmp(optarg, vsync_str[i])) { + opts.vsync = i; + break; + } + if ((sizeof(vsync_str) / sizeof(vsync_str[0])) == i) { + fputs("Invalid --vsync argument. Ignored.\n", stderr); + } +} + /** * Parse a configuration file from default location. */ @@ -3543,6 +3586,7 @@ parse_config(char *cpath, struct options_tmp *pcfgtmp) { config_t cfg; int ival = 0; double dval = 0.0; + const char *sval = NULL; f = open_config_file(cpath, &path); if (!f) { @@ -3637,10 +3681,15 @@ parse_config(char *cpath, struct options_tmp *pcfgtmp) { &opts.detect_client_opacity); // --refresh-rate lcfg_lookup_int(&cfg, "refresh-rate", &opts.refresh_rate); + // --vsync + if (config_lookup_string(&cfg, "vsync", &sval)) + parse_vsync(sval); // --alpha-step config_lookup_float(&cfg, "alpha-step", &opts.alpha_step); // --paint-on-overlay lcfg_lookup_bool(&cfg, "paint-on-overlay", &opts.paint_on_overlay); + // --sw-opti + lcfg_lookup_bool(&cfg, "sw-opti", &opts.sw_opti); // --shadow-exclude { config_setting_t *setting = @@ -3709,15 +3758,10 @@ get_cfg(int argc, char *const *argv) { { "alpha-step", required_argument, NULL, 271 }, { "dbe", no_argument, NULL, 272 }, { "paint-on-overlay", no_argument, NULL, 273 }, + { "sw-opti", no_argument, NULL, 274 }, // Must terminate with a NULL entry { NULL, 0, NULL, 0 }, }; - const static char * const vsync_str[] = { - "none", // VSYNC_NONE - "sw", // VSYNC_SW - "drm", // VSYNC_DRM - "opengl", // VSYNC_OPENGL - }; struct options_tmp cfgtmp = { .no_dock_shadow = False, @@ -3879,17 +3923,7 @@ get_cfg(int argc, char *const *argv) { break; case 270: // --vsync - { - vsync_t i; - for (i = 0; i < (sizeof(vsync_str) / sizeof(vsync_str[0])); ++i) - if (!strcasecmp(optarg, vsync_str[i])) { - opts.vsync = i; - break; - } - if ((sizeof(vsync_str) / sizeof(vsync_str[0])) == i) { - fputs("Invalid --vsync argument. Ignored.\n", stderr); - } - } + parse_vsync(optarg); break; case 271: // --alpha-step @@ -3903,6 +3937,10 @@ get_cfg(int argc, char *const *argv) { // --paint-on-overlay opts.paint_on_overlay = True; break; + case 274: + // --sw-opti + opts.sw_opti = True; + break; default: usage(); break; @@ -4018,12 +4056,12 @@ update_refresh_rate(Display *dpy) { } /** - * Initialize software VSync. + * Initialize refresh-rated based software optimization. * * @return True for success, False otherwise */ static Bool -vsync_sw_init(void) { +sw_opti_init(void) { // Prepare refresh rate // Check if user provides one refresh_rate = opts.refresh_rate; @@ -4047,21 +4085,6 @@ vsync_sw_init(void) { return True; } -/** - * Get current time in struct timespec. - * - * Note its starting time is unspecified. - */ -static inline struct timespec -get_time_timespec(void) { - struct timespec tm = { 0 }; - - clock_gettime(CLOCK_MONOTONIC, &tm); - - // Return a time of all 0 if the call fails - return tm; -} - /** * Get the smaller number that is bigger than dividend and is * N times of divisor. @@ -4079,19 +4102,35 @@ lceil_ntimes(long dividend, long divisor) { } /** - * Calculate time for which the program should wait for events if vsync_sw is - * enabled. + * Wait for events until next paint. + * + * Optionally use refresh-rate based optimization to reduce painting. * - * @param timeout old timeout value, never negative! - * @return time to wait, in struct timespec + * @param fd struct pollfd used for poll() + * @param timeout second timeout (fading timeout) + * @return > 0 if we get some events, 0 if timeout is reached, < 0 on + * problems */ -static struct timespec -vsync_sw_ntimeout(int timeout) { +static int +evpoll(struct pollfd *fd, int timeout) { + // Always wait infinitely if asked so, to minimize CPU usage + if (timeout < 0) { + int ret = poll(fd, 1, timeout); + // Reset fade_time so the fading steps during idling are not counted + fade_time = get_time_ms(); + return ret; + } + + // Just do a poll() if we are not using optimization + if (!opts.sw_opti) + return poll(fd, 1, timeout); + // Convert the old timeout to struct timespec struct timespec next_paint_tmout = { .tv_sec = timeout / MS_PER_SEC, .tv_nsec = timeout % MS_PER_SEC * (NS_PER_SEC / MS_PER_SEC) }; + // Get the nanosecond offset of the time when the we reach the timeout // I don't think a 32-bit long could overflow here. long target_relative_offset = (next_paint_tmout.tv_nsec + get_time_timespec().tv_nsec - paint_tm_offset) % NS_PER_SEC; @@ -4100,19 +4139,19 @@ vsync_sw_ntimeout(int timeout) { assert(target_relative_offset >= 0); - // If the target time is sufficiently close to a VSync time, don't add + // If the target time is sufficiently close to a refresh time, don't add // an offset, to avoid certain blocking conditions. - if ((target_relative_offset % NS_PER_SEC) < VSYNC_SW_TOLERANCE) - return next_paint_tmout; + if ((target_relative_offset % NS_PER_SEC) < SW_OPTI_TOLERANCE) + return poll(fd, 1, timeout); - // Add an offset so we wait until the next VSync after timeout + // Add an offset so we wait until the next refresh after timeout next_paint_tmout.tv_nsec += lceil_ntimes(target_relative_offset, refresh_intv) - target_relative_offset; if (next_paint_tmout.tv_nsec > NS_PER_SEC) { next_paint_tmout.tv_nsec -= NS_PER_SEC; ++next_paint_tmout.tv_sec; } - return next_paint_tmout; + return ppoll(fd, 1, &next_paint_tmout, NULL); } /** @@ -4211,57 +4250,31 @@ vsync_opengl_wait(void) { #endif /** - * Wait for next vsync and timeout unless new events appear. - * - * @param fd struct pollfd used for poll() - * @param timeout second timeout (fading timeout) - * @return > 0 if we get some events, 0 if timeout is reached, < 0 on - * problems + * Wait for next VSync. */ -static Bool -vsync_wait(Display *dpy, struct pollfd *fd, int timeout) { - // Always wait infinitely if asked so, to minimize CPU usage - if (timeout < 0) { - int ret = poll(fd, 1, timeout); - // Reset fade_time so the fading steps during idling are not counted - fade_time = get_time_ms(); - return ret; - } - +static void +vsync_wait(void) { if (VSYNC_NONE == opts.vsync) - return poll(fd, 1, timeout); - - // vsync_sw: Wait until the next sync right after next fading timeout - if (VSYNC_SW == opts.vsync) { - struct timespec new_tmout = vsync_sw_ntimeout(timeout); - // printf("ppoll(): %3ld:%09ld\n", new_tmout.tv_sec, new_tmout.tv_nsec); - return ppoll(fd, 1, &new_tmout, NULL); - } + return; #ifdef CONFIG_VSYNC_DRM - // vsync_drm: We are not accepting events when waiting for next sync, - // so I guess this would generate a latency of at most one frame. I'm - // not sure if it's possible to add some smart logic in vsync_drm_wait() - // to avoid this problem, unless I could find more documentation... if (VSYNC_DRM == opts.vsync) { vsync_drm_wait(); - return 0; + return; } #endif #ifdef CONFIG_VSYNC_OPENGL - // vsync_opengl: Same one-frame-latency issue, well, not sure how to deal it - // here. if (VSYNC_OPENGL == opts.vsync) { vsync_opengl_wait(); - return 0; + return; } #endif // This place should not reached! assert(0); - return 0; + return; } /** @@ -4391,7 +4404,7 @@ main(int argc, char **argv) { } // Query X RandR - if (VSYNC_SW == opts.vsync && !opts.refresh_rate) { + if (opts.sw_opti && !opts.refresh_rate) { if (XRRQueryExtension(dpy, &randr_event, &randr_error)) randr_exists = True; else @@ -4429,9 +4442,12 @@ main(int argc, char **argv) { register_cm((VSYNC_OPENGL == opts.vsync)); - // Initialize software/DRM/OpenGL VSync - if ((VSYNC_SW == opts.vsync && !vsync_sw_init()) - || (VSYNC_DRM == opts.vsync && !vsync_drm_init()) + // Initialize software optimization + if (opts.sw_opti) + opts.sw_opti = sw_opti_init(); + + // Initialize DRM/OpenGL VSync + if ((VSYNC_DRM == opts.vsync && !vsync_drm_init()) || (VSYNC_OPENGL == opts.vsync && !vsync_opengl_init())) opts.vsync = VSYNC_NONE; @@ -4513,11 +4529,7 @@ main(int argc, char **argv) { ufd.fd = ConnectionNumber(dpy); ufd.events = POLLIN; -#ifdef DEBUG_REPAINT - struct timespec last_paint = get_time_timespec(); -#endif - - if (VSYNC_SW == opts.vsync) + if (opts.sw_opti) paint_tm_offset = get_time_timespec().tv_nsec; reg_ignore_expire = True; @@ -4534,7 +4546,7 @@ main(int argc, char **argv) { Bool ev_received = False; while (QLength(dpy) - || (vsync_wait(dpy, &ufd, + || (evpoll(&ufd, (ev_received ? 0: (idling ? -1: fade_timeout()))) > 0)) { XNextEvent(dpy, &ev); ev_handle((XEvent *) &ev); @@ -4547,14 +4559,6 @@ main(int argc, char **argv) { t = paint_preprocess(dpy, list); if (all_damage && !is_region_empty(dpy, all_damage)) { -#ifdef DEBUG_REPAINT - struct timespec now = get_time_timespec(); - struct timespec diff = { 0 }; - timespec_subtract(&diff, &now, &last_paint); - printf("[ %5ld:%09ld ] ", diff.tv_sec, diff.tv_nsec); - last_paint = now; -#endif - static int paint; paint_all(dpy, all_damage, t); reg_ignore_expire = False; diff --git a/compton.h b/compton.h index 77c67ed3e..6ae31814b 100644 --- a/compton.h +++ b/compton.h @@ -111,7 +111,7 @@ extern struct timeval time_start; #define WINDOW_ARGB 2 #define FADE_DELTA_TOLERANCE 0.2 -#define VSYNC_SW_TOLERANCE 1000 +#define SW_OPTI_TOLERANCE 1000 #define NS_PER_SEC 1000000000L #define US_PER_SEC 1000000L @@ -286,7 +286,6 @@ typedef struct _win { typedef enum _vsync_t { VSYNC_NONE, - VSYNC_SW, VSYNC_DRM, VSYNC_OPENGL, } vsync_t; @@ -313,9 +312,11 @@ typedef struct _options { /// Whether to work under synchronized mode for debugging. Bool synchronize; - // VSync + // VSync and software optimization /// User-specified refresh rate. int refresh_rate; + /// Whether to enable refresh-rate-based software optimization. + Bool sw_opti; /// VSync method to use; vsync_t vsync; /// Whether to enable double buffer. @@ -619,6 +620,21 @@ timespec_subtract(struct timespec *result, return x->tv_sec < y->tv_sec; } +/** + * Get current time in struct timespec. + * + * Note its starting time is unspecified. + */ +static inline struct timespec +get_time_timespec(void) { + struct timespec tm = { 0 }; + + clock_gettime(CLOCK_MONOTONIC, &tm); + + // Return a time of all 0 if the call fails + return tm; +} + /** * Print time passed since program starts execution. * @@ -1136,10 +1152,10 @@ static void update_refresh_rate(Display *dpy); static Bool -vsync_sw_init(void); +sw_opti_init(void); -static struct timespec -vsync_sw_ntimeout(int timeout); +static int +evpoll(struct pollfd *fd, int timeout); static Bool vsync_drm_init(void); @@ -1157,8 +1173,8 @@ static void vsync_opengl_wait(void); #endif -static Bool -vsync_wait(Display *dpy, struct pollfd *fd, int timeout); +static void +vsync_wait(void); static void init_alpha_picts(Display *dpy);