Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: "Carlos E.R." Newsgroups: alt.comp.os.windows-11 Subject: Re: memory usage vs fan usage Date: Fri, 18 Apr 2025 21:33:00 +0200 Lines: 93 Message-ID: References: <1dqvnjtw9l7d2$.dlg@v.nguard.lh> <1r8wxmd635x99.dlg@v.nguard.lh> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net 9YAjlCv9UaLrwqzt+LXsUgfrIgssTNNhu3DaDmbnHmR/fY45P0 X-Orig-Path: Telcontar.valinor!not-for-mail Cancel-Lock: sha1:/zpq+1Irg20z3bI5f/Pq2oP6f9A= sha256:LHv0hTxQQKaajA5MQiaewljFqkgzc4CeM3FvT+PmkZg= User-Agent: Mozilla Thunderbird Content-Language: es-ES, en-CA In-Reply-To: <1r8wxmd635x99.dlg@v.nguard.lh> Xref: csiph.com alt.comp.os.windows-11:18493 On 2025-04-18 18:13, VanguardLH wrote: > "Carlos E.R." wrote: > >> The operating system would know, and decide not to use part of the >> memory. Switch it off, no contents to worry about losing. But I suspect >> the power saved would be minimal. > > I have 64 GB of RAM. That would be a hell of a lot of writes to > remember (64 GB) to know if some memory had been written in the past. > With my 64 GB of RAM, another 64 GB of RAM or cache on very slow disk > would be need to track which addresses had been written in the RAM. Or, > alternatively, I could only use 32 GB of my RAM, because the other 32 GB > was used for tracking past writes. > > This history cache to record which addresses were accessed wouldn't need > to be as big as the main RAM that stores the data, or maybe a bit > mapping could be used to equate an address in RAM to a bit in history > RAM, but the history would have to record all writes however long the > computer had been powered up, including sleep modes. More RAM would be > needed to track writes to main RAM. You certainly wouldn't use a > history cache on a drive. No, if the feature existed it would switch on/off large blocks of memory, probably entire modules or chips. > >>> Okay, but it takes a moment to come out of sleep mode, and that would >>> be highly impactful to the performance and responsiveness of the OS >>> and apps if the computer were constantly diving into deep sleep to >>> immediately come out of it. >> >> Not important, because switching a memory module on would happen when >> loading more software, or when some application demands a lot more >> memory. This would be a rare event. > > No, the moment any process needed a single byte from a memory module > would require the memory module to be instantly turned on from sleep. No. It would happen only when a program wants to assign, for instance, a block of 100 MB of memory, and the operating system decides whether to use swap or activate more ram. Accessing a byte? No, that byte is already assigned and live. A ram module can not be switched off while any code holds addresses on it. > That includes the OS along with any services and backgrounded programs. > Yes, executables have an image loaded into memory when they get loaded, > but memory is also accessed by running processes. ALL processes would > have to get suspended to prevent any memory access during sleep. Well, > that's when sleeping, and neither you nor the computer can do anything, > so it appears all memory modules can go into a partial reduced power > mode, but require constant refreshing and voltage can never be reduced. > The constant refreshing to retain content in memory and required voltage > means the memory module doesn't sleep, it just has a lower duty cycle to > reduce its power consumption, but then DRAM doesn't consume much power. > >> It might be interesting for phones and other battery operated devices. >> >> You make me wonder: mobile phones use dynamic ram, or static ram? >> >> I think calculators use static. > > Static RAM holds its data as long as it has power. Does not require > refreshing versus dynamic RAM where data decays in seconds and needs > constant refreshing. SRAM is faster than DRAM, but not as dense as > DRAM. SRAM is used in cell phones and wearables, and as a cache for the > CPU registers (i.e., microprocessors have SRAM), but then nowhere near > as much memory is needed as for main system memory where programs are > loaded and data is stored. > > There is also NVSRAM where batteries are impractical to preserve data, > like in medical equipment where data loss is intolerable from a power > loss. I've never looked into PSRAM (Pseudostatic SRAM) which puts the > refresh logic inside the memory module. > > I don't see SRAM sold at Newegg. I've never had a desktop build nor > pried into a laptop that had sockets for SRAM, just for DRAM. I did > find SRAM sold online, like at: > > https://www.mouser.com/c/semiconductors/memory-ics/sram/ > > 4 GB SRAM (134,217,728 x 32) was the largest they list. They didn't > show pricing since it was out of stock. It is a BGA package, so has to > get soldered which reflects its specialty use, not slid into a socket. > > I suspect Paul, based on the technical detail of his posts, has dug more > into where SRAM might get used. -- Cheers, Carlos.