Re: [PATCH linux-next V2] tty: Disable default console blanking interval
On Thu, 23 Mar 2017, Austin S. Hemmelgarn wrote: > On 2017-03-22 21:32, Scot Doyle wrote: > > On Wed, 22 Mar 2017, Tim Gardner wrote: > > > BugLink: http://bugs.launchpad.net/bugs/869017 > > > > > > Console blanking is not enabling DPMS power saving (thereby negating any > > > power-saving benefit), and is simply turning the screen content blank. > > > This > > > means that any crash output is invisible which is unhelpful on a server > > > (virtual or otherwise). > > > > > > Furthermore, CRT burn in concerns should no longer govern the default > > > case. > > > Affected users could always set consoleblank on the kernel command line. > > > > Does screen blanking save some power by disabling the cursor blink? > > > Unless you're dealing with ancient hardware, the difference in power usage is > probably on the order of single digit micro-watts, which is not worth worrying > about on almost anything you would expect to have a console display connected > to. > Here's a little more information. powertop estimates fb_flashcursor consumes 24 to 28 milliwatts on a Haswell laptop with drm framebuffer console. Since some commercial virtual machine providers include an emulated vga card, this table shows power usage estimates of a KVM-accelerated QEMU 2.8.0 vm using QEMU's default vga card. The host and guest are Debian Stretch with kernel 4.9.6. QEMUQEMU w/ SDL with no Minute display display -- --- --- 0 1500mW 1540mW 131076.1 292 0.403 1 266 57.1 320 58.4 307 56.6 2 318 55.9 268 57 329 56.1 3 263 54.7 264 55.7 265 55.5 4 313 56.1 341 55.2 311 55.6 5 317 55.8 340 57 342 55.6 6 342 55.3 278 54.9 260 55.8 7 261 55.3 260 55.2 261 55 8 307 55.8 262 55.3 259 55.9 9 260 56.7 337 55.8 270 56.2 10 224 27.2 222 27.2 220 27.5 11 221 27.8 220 27.3 220 27.6 12 220 27.6 219 27 218 26.9 13 218 27.7 217 26.9 220 27.7 14 220 27.5 221 27.4 220 27.7 15 221 27.1 221 27.8 220 28.3 16 221 26.7 220 27.5 220 27.2 17 221 26.8 221 27.1 219 27.6 18 219 27.1 218 26.8 218 27.4 19 220 27.4 218 27.4 218 27.6 20 220 26.6
Re: [PATCH linux-next V2] tty: Disable default console blanking interval
On Thu, 23 Mar 2017, Austin S. Hemmelgarn wrote: > On 2017-03-22 21:32, Scot Doyle wrote: > > On Wed, 22 Mar 2017, Tim Gardner wrote: > > > BugLink: http://bugs.launchpad.net/bugs/869017 > > > > > > Console blanking is not enabling DPMS power saving (thereby negating any > > > power-saving benefit), and is simply turning the screen content blank. > > > This > > > means that any crash output is invisible which is unhelpful on a server > > > (virtual or otherwise). > > > > > > Furthermore, CRT burn in concerns should no longer govern the default > > > case. > > > Affected users could always set consoleblank on the kernel command line. > > > > Does screen blanking save some power by disabling the cursor blink? > > > Unless you're dealing with ancient hardware, the difference in power usage is > probably on the order of single digit micro-watts, which is not worth worrying > about on almost anything you would expect to have a console display connected > to. > Here's a little more information. powertop estimates fb_flashcursor consumes 24 to 28 milliwatts on a Haswell laptop with drm framebuffer console. Since some commercial virtual machine providers include an emulated vga card, this table shows power usage estimates of a KVM-accelerated QEMU 2.8.0 vm using QEMU's default vga card. The host and guest are Debian Stretch with kernel 4.9.6. QEMUQEMU w/ SDL with no Minute display display -- --- --- 0 1500mW 1540mW 131076.1 292 0.403 1 266 57.1 320 58.4 307 56.6 2 318 55.9 268 57 329 56.1 3 263 54.7 264 55.7 265 55.5 4 313 56.1 341 55.2 311 55.6 5 317 55.8 340 57 342 55.6 6 342 55.3 278 54.9 260 55.8 7 261 55.3 260 55.2 261 55 8 307 55.8 262 55.3 259 55.9 9 260 56.7 337 55.8 270 56.2 10 224 27.2 222 27.2 220 27.5 11 221 27.8 220 27.3 220 27.6 12 220 27.6 219 27 218 26.9 13 218 27.7 217 26.9 220 27.7 14 220 27.5 221 27.4 220 27.7 15 221 27.1 221 27.8 220 28.3 16 221 26.7 220 27.5 220 27.2 17 221 26.8 221 27.1 219 27.6 18 219 27.1 218 26.8 218 27.4 19 220 27.4 218 27.4 218 27.6 20 220 26.6
Re: [PATCH linux-next V2] tty: Disable default console blanking interval
On 2017-03-22 21:32, Scot Doyle wrote: On Wed, 22 Mar 2017, Tim Gardner wrote: BugLink: http://bugs.launchpad.net/bugs/869017 Console blanking is not enabling DPMS power saving (thereby negating any power-saving benefit), and is simply turning the screen content blank. This means that any crash output is invisible which is unhelpful on a server (virtual or otherwise). Furthermore, CRT burn in concerns should no longer govern the default case. Affected users could always set consoleblank on the kernel command line. Does screen blanking save some power by disabling the cursor blink? Unless you're dealing with ancient hardware, the difference in power usage is probably on the order of single digit micro-watts, which is not worth worrying about on almost anything you would expect to have a console display connected to.
Re: [PATCH linux-next V2] tty: Disable default console blanking interval
On 2017-03-22 21:32, Scot Doyle wrote: On Wed, 22 Mar 2017, Tim Gardner wrote: BugLink: http://bugs.launchpad.net/bugs/869017 Console blanking is not enabling DPMS power saving (thereby negating any power-saving benefit), and is simply turning the screen content blank. This means that any crash output is invisible which is unhelpful on a server (virtual or otherwise). Furthermore, CRT burn in concerns should no longer govern the default case. Affected users could always set consoleblank on the kernel command line. Does screen blanking save some power by disabling the cursor blink? Unless you're dealing with ancient hardware, the difference in power usage is probably on the order of single digit micro-watts, which is not worth worrying about on almost anything you would expect to have a console display connected to.
Re: [PATCH linux-next V2] tty: Disable default console blanking interval
On Wed, 22 Mar 2017, Tim Gardner wrote: > BugLink: http://bugs.launchpad.net/bugs/869017 > > Console blanking is not enabling DPMS power saving (thereby negating any > power-saving benefit), and is simply turning the screen content blank. This > means that any crash output is invisible which is unhelpful on a server > (virtual or otherwise). > > Furthermore, CRT burn in concerns should no longer govern the default case. > Affected users could always set consoleblank on the kernel command line. Does screen blanking save some power by disabling the cursor blink?
Re: [PATCH linux-next V2] tty: Disable default console blanking interval
On Wed, 22 Mar 2017, Tim Gardner wrote: > BugLink: http://bugs.launchpad.net/bugs/869017 > > Console blanking is not enabling DPMS power saving (thereby negating any > power-saving benefit), and is simply turning the screen content blank. This > means that any crash output is invisible which is unhelpful on a server > (virtual or otherwise). > > Furthermore, CRT burn in concerns should no longer govern the default case. > Affected users could always set consoleblank on the kernel command line. Does screen blanking save some power by disabling the cursor blink?
