* [Qemu-devel] Speed up hack [not found] <200405170918.i4H9I4OR001702@treas.simtreas.ru> @ 2004-05-17 16:22 ` Vladimir N. Oleynik 2004-05-17 21:12 ` Fabrice Bellard 0 siblings, 1 reply; 2+ messages in thread From: Vladimir N. Oleynik @ 2004-05-17 16:22 UTC (permalink / raw) To: qemu-devel Hi. I generate little speed up hack: 1) new TICKS_BEFORE_POLL constant from make cpu loop before call poll(). 2) call DMA_run() if sb16 or floppy present 3) also, for extreme overclocker: if change MAX_FD from 2 to 1, you can make very little speed up also ;-) --- vl.c~ 2004-05-17 20:15:26.000000000 +0400 +++ vl.c 2004-05-17 19:52:44.000000000 +0400 @@ -1634,6 +1634,8 @@ } } +#define TICKS_BEFORE_POLL 100 + int main_loop(void) { #ifndef _WIN32 @@ -1641,6 +1643,7 @@ IOHandlerRecord *ioh, *ioh_next; uint8_t buf[4096]; int n, max_size; + int tick_before_poll=TICKS_BEFORE_POLL; #endif int ret, timeout; CPUState *env = global_env; @@ -1670,6 +1673,11 @@ Sleep(timeout); #else + if(tick_before_poll!=0 && timeout==0) { + tick_before_poll--; + goto ltick_before_poll; + } + tick_before_poll=TICKS_BEFORE_POLL; /* poll any events */ /* XXX: separate device handlers from system ones */ pf = ufds; @@ -1741,6 +1749,7 @@ } #endif + ltick_before_poll: #endif if (vm_running) { @@ -1750,10 +1759,18 @@ if (audio_enabled) { /* XXX: add explicit timer */ SB16_run(); - } + DMA_run(); + } else { + int i; - /* run dma transfers, if any */ - DMA_run(); + /* run dma transfers, if any */ + for(i = 0; i < MAX_FD; i++) { + if(fd_table[i]) { + DMA_run(); + break; + } + } + } } /* real time timers */ --w vodz ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Qemu-devel] Speed up hack 2004-05-17 16:22 ` [Qemu-devel] Speed up hack Vladimir N. Oleynik @ 2004-05-17 21:12 ` Fabrice Bellard 0 siblings, 0 replies; 2+ messages in thread From: Fabrice Bellard @ 2004-05-17 21:12 UTC (permalink / raw) To: qemu-devel Can you estimate the speed gains ? I am especially interested by the poll() overhead. For the rest, optimizing DMA_run() would be simpler and more efficient. Fabrice. Vladimir N. Oleynik wrote: > Hi. > > I generate little speed up hack: > > 1) new TICKS_BEFORE_POLL constant from make cpu loop before > call poll(). > 2) call DMA_run() if sb16 or floppy present > 3) also, for extreme overclocker: if change MAX_FD from 2 to 1, > you can make very little speed up also ;-) > > > --- vl.c~ 2004-05-17 20:15:26.000000000 +0400 > +++ vl.c 2004-05-17 19:52:44.000000000 +0400 > @@ -1634,6 +1634,8 @@ > } > } > > +#define TICKS_BEFORE_POLL 100 > + > int main_loop(void) > { > #ifndef _WIN32 > @@ -1641,6 +1643,7 @@ > IOHandlerRecord *ioh, *ioh_next; > uint8_t buf[4096]; > int n, max_size; > + int tick_before_poll=TICKS_BEFORE_POLL; > #endif > int ret, timeout; > CPUState *env = global_env; > @@ -1670,6 +1673,11 @@ > Sleep(timeout); > #else > > + if(tick_before_poll!=0 && timeout==0) { > + tick_before_poll--; > + goto ltick_before_poll; > + } > + tick_before_poll=TICKS_BEFORE_POLL; > /* poll any events */ > /* XXX: separate device handlers from system ones */ > pf = ufds; > @@ -1741,6 +1749,7 @@ > } > #endif > > + ltick_before_poll: > #endif > > if (vm_running) { > @@ -1750,10 +1759,18 @@ > if (audio_enabled) { > /* XXX: add explicit timer */ > SB16_run(); > - } > + DMA_run(); > + } else { > + int i; > > - /* run dma transfers, if any */ > - DMA_run(); > + /* run dma transfers, if any */ > + for(i = 0; i < MAX_FD; i++) { > + if(fd_table[i]) { > + DMA_run(); > + break; > + } > + } > + } > } > > /* real time timers */ > > > --w > vodz > > > _______________________________________________ > Qemu-devel mailing list > Qemu-devel@nongnu.org > http://mail.nongnu.org/mailman/listinfo/qemu-devel > ^ permalink raw reply [flat|nested] 2+ messages in thread
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2004-05-17 16:22 ` [Qemu-devel] Speed up hack Vladimir N. Oleynik
2004-05-17 21:12 ` Fabrice Bellard
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