Bulat_Ziganshin

5 ms·

1.
by Bulat_Ziganshin 2mo ago
"A lot" is quite a bit of an overstatement. I don't remember the exact numbers, but my program, which updated stats (about 100 chars + '\r') every 0.1s, was becoming noticeably faster if these stats were disabled. s
2.
by Bulat_Ziganshin 4mo ago
No, but LPDDR means soldered, there are no LPDDR dimms
3.
by Bulat_Ziganshin 4mo ago
They didn't say that Mediatek made the cpu sores. Grace is NVidia's own cpu arm cores. I bet that Mediatek made other parts of SoC necessary for a notebook
4.
by Bulat_Ziganshin 4mo ago
I think that Nvidia made GPU and CPU, and Mediatek made other parts of SoC necessary for a notebook. Grace is Nvidia's own CPU ARM core
5.
by Bulat_Ziganshin 10mo ago
They compare HGEMM implementations. At least CUBLAS has HGEMM functions. HGEMM means half-precision (i.e. FP16) general matrix multiplication
6.
by Bulat_Ziganshin 2y ago
just to make you even more paranoid - zen2/4 (and probably e-cores and zen5) can rename memory operands too (you start to do strange things when Intel limits you to 16 registers)! so today it needs to go through SSD or maybe the networ
7.
by Bulat_Ziganshin 2y ago
what about 8-bit ANDN? SHL essentially uses CL, so it may be because 8-bit subregister of "constant register" isn't present on the bypass network
8.
by Bulat_Ziganshin 2y ago
I once searched github for simd libraries, sorted by popularity, and added most popular of them to my list: https://github.com/stars/Bulat-Ziganshin/lists/simd indeed, highway is the popularity leader, it imp
9.
by Bulat_Ziganshin 2y ago
with m/t, the algorithm is memory-bound, so the performance should be determined strictly by the memory throughput
10.
by Bulat_Ziganshin 2y ago
JOIN SQL operation is another usecase
11.
by Bulat_Ziganshin 2y ago
it's how Google managed to convince young people all over the world to start reading those crappy A&DS books
12.
by Bulat_Ziganshin 2y ago
Intel shifts anyway mask out higher bits of CL, this hurts sometimes e.g. when you need to shift by 1..64 bits
13.
by Bulat_Ziganshin 2y ago
high-performance sorting algos do either merging or partitioning. I.e., you merge R input streams into one, or split one input stream into R (for quick, radix and sample sort). 1. For merge sort of N elements, you have to perform log(N)&#x2
14.
by Bulat_Ziganshin 2y ago
higher throughput means we can serve more people, not that anyone will be served faster. it's like a multi-lane highway
15.
by Bulat_Ziganshin 2y ago
because THIS code becomes faster once RCX is saved and restored during the interrupt call
16.
by Bulat_Ziganshin 2y ago
we set CX only once and then use it 10000 times. the problem is not the slow calculation of CX per se, but the slow shift once we got CX from the renamer
17.
by Bulat_Ziganshin 2y ago
add3 operation will have 3 inputs, though. do we have other integer operations with 3 64-bit inputs?
18.
by Bulat_Ziganshin 2y ago
except that we need max() here :)
19.
by Bulat_Ziganshin 2y ago
maybe, the bypass network doesn't include these "constant registers"? a bit like zen5 where some 1-cycle SIMD ops are executed in 2 cycles, probably for shortcomings of the same network
20.
by Bulat_Ziganshin 2y ago
afaik, 7-zip filters can't have multiple inputs (at the encoding stage). multiple outputs are necessary for filters that output multiple independent data streams such as bcj2. and they are equally useful for archivers and compressors.
21.
by Bulat_Ziganshin 2y ago
only in indirect way - simpler format could allow to find another real maintainer *or even continue to maintain it himself), because it has less features. but I think xz won the linux-lzma-archive formats war exactly because it was more com
22.
by Bulat_Ziganshin 2y ago
the installation process itself executes xz scripts which can make any (?) modifications to the system
23.
by Bulat_Ziganshin 2y ago
1. both lzip and xz are using lzma compression library internally, so there is no difference in their compression ratio/speed 2. lzma compression is LZ + markov chains, while zstd is LZ + order-0 entropy coder (similar to zlib, rar and
24.
by Bulat_Ziganshin 2y ago
even worse, I have Punto switcher that automatically switches language when I start typing. With default config, it changes latin c to russian one because russian language includes word "c" while it's non-sense in English. an
25.
by Bulat_Ziganshin 2y ago
my understanding is that any Debian/RPM-based Linux running sshd would become vulnerable in a year or two. The best equivalent of this exploit is the One Ring. So the really strange thing is why they put so little effort into making th
26.
by Bulat_Ziganshin 2y ago
Collin worked on XZ and its predecessor ~15 years. It seems that he did that for free, at least in recent times. Anyone will lose motivation to work for free over this period of time. At the same time, XZ became a cornerstone of major Linxu
27.
by Bulat_Ziganshin 2y ago
the motivation is probably "get foot in the door". the attacker also made a few documentation-only PRs in various repos, but having code PR will make him more creditable, and also would help to add more backdoors to libarchive in
28.
by Bulat_Ziganshin 2y ago
many people are patriots of their countries. if state agency would approach them proposing to have paid OSS work and help their country to fight terrorism/dictatorships/capitalists/whatever-they-believe, they will feel like k
29.
by Bulat_Ziganshin 2y ago
if I got it right, the attack uses glibc IFUNC mechanism to patch sshd (and only sshd) to directly run some code in liblzma when sshd verifies logins. so the problem is IFUNC mechanism, which has its valid uses but can be EASILY misused for
30.
by Bulat_Ziganshin 2y ago
because in order to put backdoor into xz executable, you need to infect its sources. and in order to infect the sources, you need to use a similar technique to hide the modification

More ›