On Thu, Jan 11, 2018 at 06:57:20PM +0100, Riccardo G Corsi wrote: > Hello, I've updated firmware of my I3-4170 to 0x23 (LFS 8.1 kernel 4.14.12). > > Some suggestions how to verify performance changes? Log files to look for? > > Thanks > > Riccardo > What performance changes are you expecting ?
The updated microcodes are believed to mitigate Spectre attacks. I don't know if yours is one of the updated ones, but my i7-4790 is also using 0x23 and that has a date of 2017-11-30 in dmesg. If yours is the same then yes, it is believed to include this mitigation. The revision numbers such as 0x23 are specific to the family - model - stepping, others will have very different revision numbers. If you are running a webserver, or perhaps a postgresql database, or anything requiring it to process a lot of network packets, then you might notice a slowdown. But as everybody says - it depends on your workload. My i7 is mostly used as a desktop and for building LFS and BLFS. At the moment I'm running a series of LFS builds to try to determine if there is any impact. My impression is that the variations so far are within normal tolerances, but this is the 'safe' set with the new microcode and PTI, I'll do the 'unsafe' set with 'nopti' and older microcode later. The microcode is a black box, so apart from seeing the version number and date, and the message [ 0.000000] Kernel/User page tables isolation: enabled there will be nothing in the logs. I suspect that the interesting thing will be the 'retpoline' kernel mitigation - that is still under development / review and needs an updated gcc. I plan to test that eventually. In the meantime, although I don't regard the phoronix testsuite as generally useful, there are some tests at https://www.phoronix.com/scan.php?page=article&item=pre-pcid-kptiretpoline&num=1 But I think these are all from one run of each test, and my view is that most changes are probably only the normal variability (e.g. try building your own kernel config several times, from a clean start and dropping the caches - I expect the times will differ by a few seconds). From the comments there, somebody reports a severe slowdown in ffmpeg, maybe I should also test that. ĸen -- Truth, in front of her huge walk-in wardrobe, selected black leather boots with stiletto heels for such a barefaced truth. - Unseen Academicals -- http://lists.linuxfromscratch.org/listinfo/blfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
