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Meta’s renewed commitment to jemalloc
41–50 of 259 posts
Re: Meta’s renewed commitment to jemalloc
#42I recently started using Microsoft's mimalloc (via an LD_PRELOAD) to better use huge (1 GB) pages in a memory intensive program. The performance gains are significant (around 20%). It feels rather strange using an open source MS library for performance on my Linux system. There needs to be more competition in the malloc space. Between various huge page sizes and transparent huge pages, there are a lot of gains to be…
In many cases you can also do better than using malloc e.g. if you know you need a huge page, map a huge page directly with mmap
Yes, if you want to use huge pages with arbitrary alloc/free, then use a third-party malloc. If your alloc/free patterns are not arbitrary, you can do even better. We treat malloc as a magic black box but it's actually not very good.
Re: Meta’s renewed commitment to jemalloc
#43Re: Meta’s renewed commitment to jemalloc
#44Earlier quoted context omitted.
Agreed, however there is also a reason why the best ones also pack multiple GC algorithms, like in Java and .NET, because one approach doesn't fit all workloads.
Then there’s perl, which doesn’t free at all.
doesn't java also?
I heard that was a common complaint for minecraft
Re: Meta’s renewed commitment to jemalloc
#45I recently started using Microsoft's mimalloc (via an LD_PRELOAD) to better use huge (1 GB) pages in a memory intensive program. The performance gains are significant (around 20%). It feels rather strange using an open source MS library for performance on my Linux system. There needs to be more competition in the malloc space. Between various huge page sizes and transparent huge pages, there are a lot of gains to be…
I feel like the real thing that needs to change is we need a more expressive allocation interface than just malloc/realloc. I'm sure that memory allocators could do a significantly better job if they had more information about what the program was intending to do.
There are, look no further than jemalloc API surface itself:
https://jemalloc.net/jemalloc.3.html
One thing to call out: sdallocx integrates well with C++'s sized delete semantics: https://isocpp.org/files/papers/n3778.html
Re: Meta’s renewed commitment to jemalloc
#46Earlier quoted context omitted.
[flagged]
It still beat mimalloc when I checked 4-5 years ago.
You really need to benchmark your workloads, ideally with the "big 3" (jemalloc, tcmalloc, mimalloc). They all have their strengths and weaknesses.
Jemalloc can usually keep the smallest memory footprint, followed by tcmalloc.
Mimalloc can really speed things up sometimes.
As usually, YMMV.
Re: Meta’s renewed commitment to jemalloc
#47I recently started using Microsoft's mimalloc (via an LD_PRELOAD) to better use huge (1 GB) pages in a memory intensive program. The performance gains are significant (around 20%). It feels rather strange using an open source MS library for performance on my Linux system. There needs to be more competition in the malloc space. Between various huge page sizes and transparent huge pages, there are a lot of gains to be…
We evaluated a few allocators for some of our Linux apps and found (modern) tcmalloc to consistently win in time and space. Our applications are primarily written in Rust and the allocators were linked in statically (except for glibc). Unfortunately I didn't capture much context on the allocation patterns. I think in general the apps allocate and deallocate at a higher rate than most Rust apps (or more than I'd like at least).
Our results from July 2025:
rows are : ,
app1:
glibc: 215,580 KB, 133 ms
mimalloc 2.1.7: 144,092 KB, 91 ms
mimalloc 2.2.4: 173,240 KB, 280 ms
tcmalloc: 138,496 KB, 96 ms
jemalloc: 147,408 KB, 92 ms
app2, bench1
glibc: 1,165,000 KB, 1.4 s
mimalloc 2.1.7: 1,072,000 KB, 5.1 s
mimalloc 2.2.4:
tcmalloc: 1,023,000 KB, 530 ms
app2, bench2
glibc: 1,190,224 KB, 1.5 s
mimalloc 2.1.7: 1,128,328 KB, 5.3 s
mimalloc 2.2.4: 1,657,600 KB, 3.7 s
tcmalloc: 1,045,968 KB, 640 ms
jemalloc: 1,210,000 KB, 1.1 s
app3
glibc: 284,616 KB, 440 ms
mimalloc 2.1.7: 246,216 KB, 250 ms
mimalloc 2.2.4: 325,184 KB, 290 ms
tcmalloc: 178,688 KB, 200 ms
jemalloc: 264,688 KB, 230 ms
i don't recall which jemalloc was tested.
Re: Meta’s renewed commitment to jemalloc
#48First impressions: LOL, the blunt commentary in the HN thread title compared to the PR-speak of the fb.com post. Second thoughts: Actually the fb.com post is more transparent than I'd have predicted. Not bad at all. Of course it helps that they're delivering good news!
It’s still quite corporate-y, but other than the way of writing I agree it’s generally quite clear.
Re: Meta’s renewed commitment to jemalloc
#49Re: Meta’s renewed commitment to jemalloc
#50I recently started using Microsoft's mimalloc (via an LD_PRELOAD) to better use huge (1 GB) pages in a memory intensive program. The performance gains are significant (around 20%). It feels rather strange using an open source MS library for performance on my Linux system. There needs to be more competition in the malloc space. Between various huge page sizes and transparent huge pages, there are a lot of gains to be…
One of the best parts about GC languages is they tend to have much more efficient allocation/freeing because the cost is much more lumped together so it shows up better in a profile.
When it works. Many programs in GC language end up fighting the GC by allocating a large buffer and managing it by hand anyway because when performance counts you can't have allocation time in there at all. (you see this in C all the time as well)