1ad6cc0c62
This patchset brings some performance improvements and the addition of the LZO-RLE
algorithm to the kernel, also usable in zram (yup, tested, works but LZ4 is still ok for us).
The main performance improvement is for SWAP space: the locking has changed and
the swap cache is now split in 64MB trunks.
This gives us a reduction of the median page fault latency of 375%, from 15uS to 4uS,
and an improvement of 192% on the swap throughput (this includes "virtual" swap
devices, like zRAM!). The real world user experience improvement of this on a mobile
device is seen after a day or two of usage, where it usually starts losing just a little
performance due to the large amount of apps kept open in background: now I cannot
notice any more performance loss and the user experience is now basically the same as
if the phone was in its first 2 hours of boot life.
Other performance improvements include, in short:
UDP v4/v6: 10% more performance on single RX queue
Userspace applications will be faster when checking running time of threads
2-5% improvements on heavy multipliers (yeah, not a lot, but was totally free...)
Improvements on rare conditions during sparsetruncate of about 0.3% to a
way more rare around 20% improvement (that's never gonna happen, but there
is no performance drop anywhere).
Tested on SoMC Tama Akatsuki RoW
This was taken from
Repo:
https://github.com/sonyxperiadev/kernel
PR: 2039 ([2.3.2.r1.4] Performance improvements)
83 lines
2.1 KiB
C
83 lines
2.1 KiB
C
/*
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* include/linux/pagevec.h
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*
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* In many places it is efficient to batch an operation up against multiple
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* pages. A pagevec is a multipage container which is used for that.
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*/
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#ifndef _LINUX_PAGEVEC_H
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#define _LINUX_PAGEVEC_H
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/* 15 pointers + header align the pagevec structure to a power of two */
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#define PAGEVEC_SIZE 15
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struct page;
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struct address_space;
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struct pagevec {
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unsigned char nr;
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bool cold;
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bool drained;
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struct page *pages[PAGEVEC_SIZE];
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};
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void __pagevec_release(struct pagevec *pvec);
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void __pagevec_lru_add(struct pagevec *pvec);
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unsigned pagevec_lookup_entries(struct pagevec *pvec,
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struct address_space *mapping,
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pgoff_t start, unsigned nr_entries,
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pgoff_t *indices);
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void pagevec_remove_exceptionals(struct pagevec *pvec);
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unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
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pgoff_t start, unsigned nr_pages);
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unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
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struct address_space *mapping, pgoff_t *index, pgoff_t end,
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int tag);
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unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
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struct address_space *mapping, pgoff_t *index, pgoff_t end,
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int tag, unsigned max_pages);
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static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
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struct address_space *mapping, pgoff_t *index, int tag)
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{
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return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag);
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}
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static inline void pagevec_init(struct pagevec *pvec, int cold)
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{
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pvec->nr = 0;
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pvec->cold = cold;
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pvec->drained = false;
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}
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static inline void pagevec_reinit(struct pagevec *pvec)
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{
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pvec->nr = 0;
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}
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static inline unsigned pagevec_count(struct pagevec *pvec)
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{
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return pvec->nr;
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}
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static inline unsigned pagevec_space(struct pagevec *pvec)
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{
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return PAGEVEC_SIZE - pvec->nr;
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}
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/*
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* Add a page to a pagevec. Returns the number of slots still available.
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*/
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static inline unsigned pagevec_add(struct pagevec *pvec, struct page *page)
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{
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pvec->pages[pvec->nr++] = page;
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return pagevec_space(pvec);
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}
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static inline void pagevec_release(struct pagevec *pvec)
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{
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if (pagevec_count(pvec))
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__pagevec_release(pvec);
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}
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#endif /* _LINUX_PAGEVEC_H */
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