Em [2022-01-02 dom 23:38:48+0000], piorunz escreveu: > On 02/01/2022 16:33, Jorge P. de Morais Neto wrote: >> I am currently using compress-force=zstd:12 for the SSD and >> compress=zstd:12 for both HDD (internal SATA and external USB3)ยน. >> Despite the strong compression level, performance is pretty good. Yet, >> when the system settles, I intend to reduce compression level to 9 or 6 >> (as you earlier recommended). This should make performance even better, >> while saving a lot of space because most data was compressed at >> level 12. > > I run compress-force=zstd:6 on my fast PC, compress-force=zstd:3 on my > server (to give it a bit more breathing space), and also same level 3 on > my laptop. 12 is quite high for SSD, are you sure you not slowing down > peak performance of your SSD by intense CPU usage? Or is it by design, > to reduce number of writes to SSD?
Indeed I use such high compression to prolong SSD lifetime. IIUC, besides directly reducing the amount of data written, compression allows extra over-provisioning which should reduce the write amplification factor too. Level 12 compression probably hurts performance a bit, but programs still start very quickly---far quicker than they did over the HDD with ext4. This makes sense to me, because (IIUC) starting programs is read-intensive and zstd decompression is fast even on high compression levels. And surprisingly, even dpkg package installation and updates, which (IIUC) are write-intensive, are very quick too. Besides, I think I rarely need top CPU power and disk throughput at the same time. I max out the quad-core processor when compiling Guix packages but that happens on /tmp (tmpfs), so high Btrfs zstd compression does no harm. I also stress the CPU (and the integrated GPU) on the rare occasions I play Xonotic or SuperTuxKart, and Btrfs compression probably does no harm during 3D game rendering either. In conclusion, my SSD is plenty quick for my needs even with very high Btrfs zstd compression. I care more about maximizing its lifetime than having programs start a fraction of a second quicker when they already start very quickly. And when the system settles I intend to reduce Btrfs zstd compression level to 9 or 6 in an attempt to save electricity---although I am nearly always on AC power. > No, I am not on this list, where is it? Please send a link! http://vger.kernel.org/vger-lists.html#linux-btrfs Kind regards, Jorge -- - Many people hate injustice but few check the facts; this causes more injustice. Ask me about <https://stallmansupport.org> - Please adopt free/libre formats like PDF, Org, LaTeX, ODF, Opus, WebM and 7z. - Libre apps for AOSP (Replicant, LineageOS, etc.) and Android: F-Droid - https://www.gnu.org/philosophy/free-sw.html "What is free software?"