Messages in this thread Patch in this message | | | Subject | Re: [PATCH] inetpeer: use else if instead of if to reduce judgment | From | Eric Dumazet <> | Date | Fri, 26 Feb 2021 15:38:06 +0100 |
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On 2/26/21 11:57 AM, Yejune Deng wrote: > In inet_initpeers(), if si.totalram <= (8192*1024)/PAGE_SIZE, it will > be judged three times. Use else if instead of if, it only needs to be > judged once. > > Signed-off-by: Yejune Deng <yejune.deng@gmail.com> > --- > net/ipv4/inetpeer.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c > index ff327a62c9ce..07cd1f8204b3 100644 > --- a/net/ipv4/inetpeer.c > +++ b/net/ipv4/inetpeer.c > @@ -81,12 +81,12 @@ void __init inet_initpeers(void) > * <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values > * myself. --SAW > */ > - if (si.totalram <= (32768*1024)/PAGE_SIZE) > + if (si.totalram <= (8192 * 1024) / PAGE_SIZE) > + inet_peer_threshold >>= 4; /* about 128KB */ > + else if (si.totalram <= (16384 * 1024) / PAGE_SIZE) > + inet_peer_threshold >>= 2; /* about 512KB */ > + else if (si.totalram <= (32768 * 1024) / PAGE_SIZE) > inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */
If you really want to change this stuff, I would suggest updating comments, because nowadays, struct inet_peer on IA32 uses 128 bytes.
So 32768 entries would consume 4 MB, 16384 entries would consume 2 MB
and 4096 entries would consume 512KB
Another idea would be to get rid of the cascade and use something that will not need to be adjusted in the future.
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c index ff327a62c9ce9b1794104c3c924f5f2b9820ac8b..d5f486bd8c35234f99b22842e756a10531e070d6 100644 --- a/net/ipv4/inetpeer.c +++ b/net/ipv4/inetpeer.c @@ -65,7 +65,7 @@ EXPORT_SYMBOL_GPL(inet_peer_base_init); #define PEER_MAX_GC 32 /* Exported for sysctl_net_ipv4. */ -int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more +int inet_peer_threshold __read_mostly; /* start to throw entries more * aggressively at this stage */ int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */ int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */ @@ -73,20 +73,13 @@ int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min /* Called from ip_output.c:ip_init */ void __init inet_initpeers(void) { - struct sysinfo si; + u64 nr_entries; - /* Use the straight interface to information about memory. */ - si_meminfo(&si); - /* The values below were suggested by Alexey Kuznetsov - * <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values - * myself. --SAW - */ - if (si.totalram <= (32768*1024)/PAGE_SIZE) - inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */ - if (si.totalram <= (16384*1024)/PAGE_SIZE) - inet_peer_threshold >>= 1; /* about 512KB */ - if (si.totalram <= (8192*1024)/PAGE_SIZE) - inet_peer_threshold >>= 2; /* about 128KB */ + /* 1% of physical memory */ + nr_entries = div64_ul((u64)totalram_pages() << PAGE_SHIFT, + 100 * L1_CACHE_ALIGN(sizeof(struct inet_peer))); + + inet_peer_threshold = clamp_val(nr_entries, 4096, 65536 + 128); peer_cachep = kmem_cache_create("inet_peer_cache", sizeof(struct inet_peer),
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